diff --git a/Cabal-described/src/Distribution/Described/Extension.hs b/Cabal-described/src/Distribution/Described/Extension.hs
index 623e091ada8..4c5c81e46ae 100644
--- a/Cabal-described/src/Distribution/Described/Extension.hs
+++ b/Cabal-described/src/Distribution/Described/Extension.hs
@@ -1,7 +1,8 @@
 {-# LANGUAGE OverloadedStrings #-}
 {-# OPTIONS_GHC -Wno-orphans #-}
 module Distribution.Described.Extension
-  ( reKnownExtension
+  ( reEnableExtension
+  , reKnownExtension
   , reDisableExtension
   , reXs
       -- * Extension groups
@@ -44,6 +45,9 @@ instance Described Extension where
 reXs :: [KnownExtension] -> GrammarRegex a
 reXs xs = REUnion (fromString . prettyShow <$> xs)
 
+reEnableExtension :: GrammarRegex a
+reEnableExtension = "enable-extension"
+
 reKnownExtension :: GrammarRegex a
 reKnownExtension = REUnion
     [ RENamed "interactive-extension" $ reXs xGroupInteractive
diff --git a/Cabal-syntax-docs/Cabal-syntax-docs.cabal b/Cabal-syntax-docs/Cabal-syntax-docs.cabal
new file mode 100644
index 00000000000..1b4578c66de
--- /dev/null
+++ b/Cabal-syntax-docs/Cabal-syntax-docs.cabal
@@ -0,0 +1,44 @@
+cabal-version: 2.2
+name:          Cabal-syntax-docs
+version:       0
+
+library
+  default-language: Haskell2010
+  hs-source-dirs:   src
+  ghc-options:      -Wall
+  build-depends:
+    , base             >=4.11 && <4.20
+    , Cabal
+    , Cabal-described
+    , containers
+    , pretty
+    , zinza            ^>=0.2
+  exposed-modules: Cabal.Syntax.Docs.ZFields
+
+executable gen-cabal-package-syntax-docs
+  default-language: Haskell2010
+  hs-source-dirs:   cabal-package
+  ghc-options:      -Wall
+  main-is:          Main.hs
+  build-depends:
+    , base             >=4.11 && <4.20
+    , Cabal
+    , Cabal-described
+    , Cabal-syntax-docs
+    , containers
+    , pretty
+    , zinza            ^>=0.2
+
+executable gen-ghc-syntax-docs
+  default-language: Haskell2010
+  hs-source-dirs:   ghc
+  ghc-options:      -Wall
+  main-is:          Main.hs
+  build-depends:
+    , base             >=4.11 && <4.20
+    , Cabal
+    , Cabal-described
+    , Cabal-syntax-docs
+    , containers
+    , pretty
+    , zinza            ^>=0.2
diff --git a/Cabal-syntax-docs/cabal-package/Main.hs b/Cabal-syntax-docs/cabal-package/Main.hs
new file mode 100644
index 00000000000..c8b2dea4226
--- /dev/null
+++ b/Cabal-syntax-docs/cabal-package/Main.hs
@@ -0,0 +1,84 @@
+{-# LANGUAGE DeriveGeneric #-}
+module Main (main) where
+
+import Data.List                       (partition)
+import Data.Proxy                      (Proxy (..))
+import GHC.Generics                    (Generic)
+import System.Environment              (getArgs)
+import System.Exit                     (exitFailure)
+
+import Distribution.PackageDescription.FieldGrammar (buildInfoFieldGrammar, packageDescriptionFieldGrammar, testSuiteFieldGrammar)
+
+import qualified Zinza as Z
+
+import Distribution.Described
+import Distribution.Described.Extension ()
+import Distribution.Utils.GrammarRegex
+
+import Distribution.ModuleName         (ModuleName)
+import Distribution.Types.Version      (Version)
+import Distribution.Types.VersionRange (VersionRange)
+import Cabal.Syntax.Docs.ZFields
+
+main :: IO ()
+main = do
+    args <- getArgs
+    case args of
+        [tmpl] -> do
+            let (biGhc, biCabal) = partition isGhcBuildInfo $ fromReference buildInfoFieldGrammar
+            run <- Z.parseAndCompileTemplateIO tmpl
+            contents <- run $ Z
+                { zGhcBuildInfoFields       = biGhc
+                , zCabalBuildInfoFields     = biCabal
+                , zPackageDescriptionFields = fromReference packageDescriptionFieldGrammar
+                , zTestSuiteFields          = fromReference $ testSuiteFieldGrammar // buildInfoFieldGrammar
+                , zProductions              =
+                    [ zproduction "hs-string"       reHsString
+                        "String as in Haskell; it's recommended to avoid using Haskell-specific escapes."
+                    , zproduction "unqual-name"     reUnqualComponent $ unwords
+                        [ "Unqualified component names are used for package names, component names etc. but not flag names."
+                        , "Unqualified component name consist of components separated by dash, each component is non-empty alphanumeric string, with at least one alphabetic character."
+                        , "In other words, component may not look like a number."
+                        ]
+
+                    , zproduction "module-name"     (describe (Proxy :: Proxy ModuleName))
+                        "Haskell module name as recognized by Cabal parser."
+                    , zproduction "version"         (describe (Proxy :: Proxy Version))
+                        "Version is to first approximation numbers separated by dots, where leading zero is not allowed and each version digit is consists at most of nine characters."
+                    , zproduction "version-range"   (describe (Proxy :: Proxy VersionRange))
+                        "Version range syntax is recursive. Also note the set syntax added in ``cabal-version: 3.0``, set cannot be empty."
+                    ]
+                , zSpaceList                = show $ regexDoc $
+                    REMunch RESpaces1 (RENamed "element" RETodo)
+                , zCommaList                = show $ regexDoc $
+                    expandedCommaList (RENamed "element" RETodo)
+                , zOptCommaList             = show $ regexDoc $
+                    expandedOptCommaList (RENamed "element" RETodo)
+
+                , zNull                     = null
+                , zNotNull                  = not . null
+                }
+
+            putStrLn contents
+        _ -> do
+          putStrLn "Usage: generator <tmpl>"
+          exitFailure
+
+data Z = Z
+    { zGhcBuildInfoFields       :: [ZField]
+    , zCabalBuildInfoFields     :: [ZField]
+    , zPackageDescriptionFields :: [ZField]
+    , zTestSuiteFields          :: [ZField]
+    , zProductions              :: [ZProduction]
+    , zSpaceList                :: String
+    , zCommaList                :: String
+    , zOptCommaList             :: String
+    , zNull                     :: String -> Bool
+    , zNotNull                  :: String -> Bool
+    }
+  deriving (Generic)
+
+instance Z.Zinza Z where
+    toType    = Z.genericToTypeSFP
+    toValue   = Z.genericToValueSFP
+    fromValue = Z.genericFromValueSFP
diff --git a/buildinfo-reference-generator/template.zinza b/Cabal-syntax-docs/cabal-package/template.zinza
similarity index 91%
rename from buildinfo-reference-generator/template.zinza
rename to Cabal-syntax-docs/cabal-package/template.zinza
index 8ae6cffb52c..d2e7371df53 100644
--- a/buildinfo-reference-generator/template.zinza
+++ b/Cabal-syntax-docs/cabal-package/template.zinza
@@ -1,10 +1,24 @@
-.. _buildinfo-field-reference:
+.. _cabal-package-syntax:
 
-Field Syntax Reference
-======================
+Cabal Package Syntax
+====================
+
+GHC syntax
+----------
+
+Some elements of cabal package syntax are controlled by GHC. As such these are
+effectively strings passed on to GHC and that may be as far as Cabal will check
+their syntax. See the :ref:`ghc-syntax` for these elements of GHC syntax
+embedded within cabal package descriptions.
+
+- :ref:`ghc-enable-extension`
+- :ref:`ghc-disable-extension`
+{% for field in ghcBuildInfoFields %}
+- :ref:`{{field.name}}<ghc-{{field.name}}>`
+{% endfor %}
 
 Notation
----------------
+--------
 
 Field syntax is described as they are in the latest cabal file format version.
 
@@ -142,7 +156,7 @@ In the syntax definitions below the following non-terminal symbols are used:
 Build info fields
 -----------------
 
-{% for field in buildInfoFields %}
+{% for field in cabalBuildInfoFields %}
 {{ field.name }}
     * {{field.format}}
 {% if notNull field.default %}
diff --git a/Cabal-syntax-docs/ghc/Main.hs b/Cabal-syntax-docs/ghc/Main.hs
new file mode 100644
index 00000000000..a14173bdc4d
--- /dev/null
+++ b/Cabal-syntax-docs/ghc/Main.hs
@@ -0,0 +1,106 @@
+{-# LANGUAGE DeriveGeneric #-}
+module Main (main) where
+
+import GHC.Generics                    (Generic)
+import System.Environment              (getArgs)
+import System.Exit                     (exitFailure)
+
+import Distribution.PackageDescription.FieldGrammar (buildInfoFieldGrammar)
+
+import qualified Zinza as Z
+
+import Distribution.Described
+import Distribution.Described.Extension
+import Distribution.Utils.GrammarRegex
+import Cabal.Syntax.Docs.ZFields
+
+main :: IO ()
+main = do
+    args <- getArgs
+    case args of
+        [tmpl] -> do
+            let biGhc = filter isGhcBuildInfo $ fromReference buildInfoFieldGrammar
+            run <- Z.parseAndCompileTemplateIO tmpl
+            contents <- run $ Z
+                { zGhcBuildInfoFields = biGhc
+                , zProductions =
+                    [ zproduction "disable-extension" reDisableExtension
+                        "Disable a language extension by prepending the extension with \"No\"."
+                    , zproduction "enable-extension" reKnownExtension
+                        "All GHC language extensions known to cabal. There may be more and some of these may be on by default."
+                    , zproduction "interactive-extension" (reXs xGroupInteractive)
+                        "Language Extensions related to GHC interactive."
+                    , zproduction "phase-extension" (reXs xGroupPhase)
+                        "Language Extensions related to a particular GHC phase."
+                    , zproduction "syntax-extension" (reXs xGroupSyntax)
+                        "Syntax Language Extensions."
+                    , zproduction "import-export-extension" (reXs xGroupImportExport)
+                        "Import and Export Language Extensions."
+                    , zproduction "type-extension" (reXs xGroupTypes)
+                        "Language Extensions for Types."
+                    , zproduction "record-extension" (reXs xGroupRecords)
+                        "Record Language Extensions."
+                    , zproduction "deriving-extension" (reXs xGroupDeriving)
+                        "Language Extensions for deriving mechanisms."
+                    , zproduction "pattern-extension" (reXs xGroupPatterns)
+                        "Patterns Language Extensions."
+                    , zproduction "classes-instances-extension" (reXs xGroupClassesInstances)
+                        "Language Extensions for class and instance declarations."
+                    , zproduction "literal-extension" (reXs xGroupLiterals)
+                        "Literals Language Extensions."
+                    , zproduction "constraint-extension" (reXs xGroupConstraints)
+                        "Constraint Language Extensions."
+                    , zproduction "type-signature-extension" (reXs xGroupTypeSignatures)
+                        "Type Signature Language Extensions."
+                    , zproduction "binding-generalisation-extension" (reXs xGroupBindingsGeneralisation)
+                        "Language Extensions for bindings and generalisation "
+                    , zproduction "template-haskell-extension" (reXs xGroupTemplates)
+                        "Template Haskell Language Extensions."
+                    , zproduction "bang-strict-extension" (reXs xGroupBangStrict)
+                        "Bang pattern and Strict Haskell Language Extensions."
+                    , zproduction "parallel-concurrent-extension" (reXs xGroupParallelConcurrent)
+                        "Parallel and Concurrent Language Extensions."
+                    , zproduction "unboxed-primitive-extension" (reXs xGroupUnboxedPrimitive)
+                        "Unboxed types and Primitive operations Language Extensions."
+                    , zproduction "foreign-extension" (reXs xGroupForeign)
+                        "Foreign function interface (FFI) Language Extensions."
+                    , zproduction "safe-extension" (reXs xGroupSafe)
+                        "Safe Haskell Language Extensions."
+                    , zproduction "miscellaneous-extension" (reXs xGroupMiscellaneous)
+                        "Miscellaneous Language Extensions."
+                    , zproduction "bugs-extension" (reXs xGroupBugs)
+                        "Language Extensions related to GHC bugs and infelicities."
+                    , zproduction "ungrouped-extension" (reXs xUngrouped)
+                        "Language Extensions not belonging to other extension groups, includes undocumented extensions."
+                    ]
+                , zSpaceList                = show $ regexDoc $
+                    REMunch RESpaces1 (RENamed "element" RETodo)
+                , zCommaList                = show $ regexDoc $
+                    expandedCommaList (RENamed "element" RETodo)
+                , zOptCommaList             = show $ regexDoc $
+                    expandedOptCommaList (RENamed "element" RETodo)
+
+                , zNull                     = null
+                , zNotNull                  = not . null
+                }
+
+            putStrLn contents
+        _ -> do
+          putStrLn "Usage: generator <tmpl>"
+          exitFailure
+
+data Z = Z
+    { zGhcBuildInfoFields       :: [ZField]
+    , zProductions              :: [ZProduction]
+    , zSpaceList                :: String
+    , zCommaList                :: String
+    , zOptCommaList             :: String
+    , zNull                     :: String -> Bool
+    , zNotNull                  :: String -> Bool
+    }
+  deriving (Generic)
+
+instance Z.Zinza Z where
+    toType    = Z.genericToTypeSFP
+    toValue   = Z.genericToValueSFP
+    fromValue = Z.genericFromValueSFP
\ No newline at end of file
diff --git a/Cabal-syntax-docs/ghc/template.zinza b/Cabal-syntax-docs/ghc/template.zinza
new file mode 100644
index 00000000000..0272d5d99a3
--- /dev/null
+++ b/Cabal-syntax-docs/ghc/template.zinza
@@ -0,0 +1,63 @@
+.. _ghc-syntax:
+
+GHC Syntax Reference
+====================
+
+Language Extensions
+-------------------
+
+The many GHC language extensions are divided into groups of extensions
+corresponding to subsections of the GHC users' guide on language extensions.
+Those of the :ref:`ungrouped-extension <ghc-ungrouped-extension>` group are
+undocumented in the GHC users' guide.
+
+{% for production in productions %}
+.. _ghc-{{ production.name }}:
+
+{{ production.name }}
+    {{ production.description }}
+
+    .. math::
+
+        {{ production.syntax }}
+
+{% endfor %}
+
+GHC build info fields
+---------------------
+
+These are cabal package build info fields that are more related to GHC, the
+Haskell compiler, than they are to Cabal.
+
+{% for field in ghcBuildInfoFields %}
+.. _ghc-{{ field.name }}:
+
+{{ field.name }}
+    * {{field.format}}
+{% if notNull field.default %}
+    * Default: ``{{field.default}}``
+{% endif %}
+{% if notNull field.availableSince %}
+    * Available since ``cabal-version: {{field.availableSince}}``.
+{% endif %}
+{% if notNull field.deprecatedSince.fst %}
+    * Deprecated since ``cabal-version: {{field.deprecatedSince.fst}}``: {{field.deprecatedSince.snd}}
+{% endif %}
+{% if notNull field.removedIn.fst %}
+    * Removed in ``cabal-version: {{field.removedIn.fst}}``: {{field.removedIn.snd}}
+{% endif %}
+{# We show documentation link only for non deprecated fields #}
+{% if null field.deprecatedSince.fst %}
+{% if null field.removedIn.fst %}
+    * Documentation of :pkg-field:`library:{{field.name}}`
+{% endif %}
+{% endif %}
+{% if notNull field.syntax %}
+
+    .. math::
+
+        {{field.syntax}}
+{% endif %}
+
+{% endfor %}
+
diff --git a/Cabal-syntax-docs/src/Cabal/Syntax/Docs/ZFields.hs b/Cabal-syntax-docs/src/Cabal/Syntax/Docs/ZFields.hs
new file mode 100644
index 00000000000..de2ca86e50c
--- /dev/null
+++ b/Cabal-syntax-docs/src/Cabal/Syntax/Docs/ZFields.hs
@@ -0,0 +1,203 @@
+{-# LANGUAGE DeriveFunctor         #-}
+{-# LANGUAGE DeriveGeneric         #-}
+{-# LANGUAGE MultiParamTypeClasses #-}
+module Cabal.Syntax.Docs.ZFields where
+
+import Data.Map.Strict (Map)
+
+import Data.Bifunctor                  (first)
+import Data.Void                       (Void)
+import Distribution.CabalSpecVersion   (CabalSpecVersion, showCabalSpecVersion)
+import Distribution.Compat.Newtype     (pack')
+import Distribution.FieldGrammar.Class (FieldGrammar (..))
+import Distribution.Fields.Field       (FieldName)
+import Distribution.Pretty             (pretty)
+import Distribution.Simple.Utils       (fromUTF8BS)
+import GHC.Generics                    (Generic)
+
+import qualified Data.Map.Strict  as Map
+import qualified Text.PrettyPrint as PP
+
+import qualified Zinza as Z
+
+import Distribution.Described
+import Distribution.Described.Extension ()
+import Distribution.Utils.GrammarRegex
+
+ghcBuildInfoFields :: [String]
+ghcBuildInfoFields = ["default-language", "other-languages", "default-extensions", "other-extensions", "extensions"]
+
+isGhcBuildInfo :: ZField -> Bool
+isGhcBuildInfo = (`elem` ghcBuildInfoFields) . zfieldName
+
+zproduction :: String -> GrammarRegex Void -> String -> ZProduction
+zproduction name re desc = ZProduction
+    { zprodName        = name
+    , zprodSyntax      = show (regexDoc re')
+    , zprodDescription = desc
+    }
+  where
+    re' = case re of
+        RENamed _ r -> r
+        _           -> re
+
+-- also in UnitTests.Distribution.Described
+expandedCommaList :: GrammarRegex a -> GrammarRegex a
+expandedCommaList = REUnion . expandedCommaList'
+
+expandedCommaList' :: GrammarRegex a -> [GrammarRegex a]
+expandedCommaList' r =
+    [ REMunch reSpacedComma r
+    , reComma <> RESpaces <> REMunch1 reSpacedComma r
+    , REMunch1 reSpacedComma r <> RESpaces <> reComma
+    ]
+
+expandedOptCommaList :: GrammarRegex a -> GrammarRegex a
+expandedOptCommaList r = REUnion $ reSpacedList r : expandedCommaList' r
+
+data ZField = ZField
+    { zfieldName            :: String
+    , zfieldAvailableSince  :: String
+    , zfieldDeprecatedSince :: (String, String)
+    , zfieldRemovedIn       :: (String, String)
+    , zfieldFormat          :: String
+    , zfieldDefault         :: String
+    , zfieldSyntax          :: String
+    }
+  deriving (Generic)
+
+instance Z.Zinza ZField where
+    toType    = Z.genericToTypeSFP
+    toValue   = Z.genericToValueSFP
+    fromValue = Z.genericFromValueSFP
+
+data ZProduction = ZProduction
+    { zprodName        :: String
+    , zprodSyntax      :: String
+    , zprodDescription :: String
+    }
+  deriving (Generic)
+
+instance Z.Zinza ZProduction where
+    toType    = Z.genericToTypeSFP
+    toValue   = Z.genericToValueSFP
+    fromValue = Z.genericFromValueSFP
+
+-------------------------------------------------------------------------------
+-- From reference
+-------------------------------------------------------------------------------
+
+-- TODO: produce ZField
+fromReference :: Reference a a -> [ZField]
+fromReference (Reference m) =
+    [ ZField
+        { zfieldName            = fromUTF8BS n
+        , zfieldAvailableSince  = maybe "" showCabalSpecVersion (fdAvailableSince desc)
+        , zfieldDeprecatedSince = maybe ("", "") (first showCabalSpecVersion) (fdDeprecatedSince desc)
+        , zfieldRemovedIn       = maybe ("", "") (first showCabalSpecVersion) (fdRemovedIn desc)
+        , zfieldFormat          = fmt
+        , zfieldDefault         = def
+        , zfieldSyntax          = syntax
+        }
+    | (n, desc) <- Map.toList m
+    , let (fmt, def, syntax) = fromFieldDesc' (fdDescription desc)
+    ]
+
+fromFieldDesc' :: FieldDesc' -> (String, String, String)
+fromFieldDesc' (MonoidalFieldAla s)        = ("Monoidal field",  "",       show s)
+fromFieldDesc' (BooleanFieldDesc def)      = ("Boolean field",   show def, show $ describeDoc ([] :: [Bool]))
+fromFieldDesc' (OptionalFieldAla s)        = ("Optional field",  "",       show s)
+fromFieldDesc' (OptionalFieldDefAla s def) = ("Optional field",  show def, show s)
+fromFieldDesc' FreeTextField               = ("Free text field", "",      "")
+fromFieldDesc' (UniqueField s)             = ("Required field",  "",       show s)
+
+-------------------------------------------------------------------------------
+-- Reference
+-------------------------------------------------------------------------------
+
+newtype Reference a b = Reference (Map FieldName FieldDesc)
+  deriving (Functor)
+
+referenceAvailableSince :: CabalSpecVersion -> Reference a b -> Reference a b
+referenceAvailableSince v (Reference m) =
+    Reference (fmap (fieldDescAvailableSince v) m)
+
+referenceRemovedIn :: CabalSpecVersion -> String -> Reference a b -> Reference a b
+referenceRemovedIn v desc (Reference m) =
+    Reference (fmap (fieldDescRemovedIn v desc) m)
+
+referenceDeprecatedSince :: CabalSpecVersion -> String -> Reference a b -> Reference a b
+referenceDeprecatedSince v desc (Reference m) =
+    Reference (fmap (fieldDescDeprecatedSince v desc) m)
+
+(//) :: Reference a b -> Reference c d -> Reference a b
+Reference ab // Reference cd = Reference $ Map.difference ab cd
+
+fieldDescAvailableSince :: CabalSpecVersion -> FieldDesc -> FieldDesc
+fieldDescAvailableSince v d = d { fdAvailableSince = Just v }
+
+fieldDescRemovedIn :: CabalSpecVersion -> String -> FieldDesc -> FieldDesc
+fieldDescRemovedIn v desc d = d { fdRemovedIn = Just (v, desc) }
+
+fieldDescDeprecatedSince :: CabalSpecVersion -> String -> FieldDesc -> FieldDesc
+fieldDescDeprecatedSince v desc d = d { fdDeprecatedSince = Just (v, desc) }
+
+data FieldDesc = FieldDesc
+    { fdAvailableSince  :: Maybe CabalSpecVersion
+    , fdRemovedIn       :: Maybe (CabalSpecVersion, String)
+    , fdDeprecatedSince :: Maybe (CabalSpecVersion, String)
+    , fdDescription     :: FieldDesc'
+    }
+  deriving Show
+
+reference :: FieldName -> FieldDesc' -> Reference a b
+reference fn d = Reference $ Map.singleton fn $ FieldDesc Nothing Nothing Nothing d
+
+data FieldDesc'
+    = BooleanFieldDesc Bool
+    | UniqueField  PP.Doc  -- ^ not used in BuildInfo
+    | FreeTextField        -- ^ not user in BuildInfo
+    | OptionalFieldAla PP.Doc
+    | OptionalFieldDefAla PP.Doc PP.Doc
+    | MonoidalFieldAla PP.Doc
+  deriving Show
+
+instance Applicative (Reference a) where
+    pure _                      = Reference Map.empty
+    Reference f <*> Reference x = Reference (Map.union f x)
+
+instance FieldGrammar Described Reference where
+    blurFieldGrammar _ (Reference xs) = Reference xs
+
+    uniqueFieldAla fn pack _l =
+        reference fn $ UniqueField (describeDoc pack)
+
+    booleanFieldDef fn _l def =
+        reference fn $ BooleanFieldDesc def
+
+    optionalFieldAla fn pack _l =
+        reference fn $ OptionalFieldAla (describeDoc pack)
+
+    optionalFieldDefAla fn pack _l def =
+        reference fn $ OptionalFieldDefAla
+            (describeDoc pack)
+            (pretty $ pack' pack def)
+
+    freeTextField fn _l = reference fn FreeTextField
+
+    freeTextFieldDef   fn _l = reference fn FreeTextField
+    freeTextFieldDefST fn _l = reference fn FreeTextField
+
+    monoidalFieldAla fn pack _l =
+        reference fn (MonoidalFieldAla (describeDoc pack))
+
+    prefixedFields _pfx _l = Reference Map.empty
+
+    knownField _fn = Reference Map.empty -- TODO
+
+    -- hidden fields are hidden from the reference.
+    hiddenField _ = Reference Map.empty
+
+    deprecatedSince = referenceDeprecatedSince
+    removedIn       = referenceRemovedIn
+    availableSince  v _ r = referenceAvailableSince v r
\ No newline at end of file
diff --git a/Makefile b/Makefile
index cf670814edf..fe53fbfe710 100644
--- a/Makefile
+++ b/Makefile
@@ -60,13 +60,13 @@ $(TEMPLATE_PATHS) : templates/Paths_pkg.template.hs cabal-dev-scripts/src/GenPat
 
 # generated docs
 # Use cabal build before cabal run to avoid output of the build on stdout when running
-doc/buildinfo-fields-reference.rst : \
+doc/%-syntax.rst : \
   $(wildcard Cabal-syntax/src/*/*.hs Cabal-syntax/src/*/*/*.hs Cabal-syntax/src/*/*/*/*.hs) \
   $(wildcard Cabal-described/src/Distribution/Described.hs Cabal-described/src/Distribution/Utils/*.hs) \
-  buildinfo-reference-generator/src/Main.hs \
-  buildinfo-reference-generator/template.zinza
-	cabal build --project-file=cabal.project.buildinfo buildinfo-reference-generator
-	cabal run --project-file=cabal.project.buildinfo buildinfo-reference-generator buildinfo-reference-generator/template.zinza | tee $@
+  Cabal-syntax-docs/$*/Main.hs \
+  Cabal-syntax-docs/$*/template.zinza
+	cabal build --project-file=cabal.project.docs gen-%-syntax-docs
+	cabal run --project-file=cabal.project.docs gen-%-syntax-docs Cabal-syntax-docs/$*/template.zinza | tee $@
 	git diff --exit-code $@
 
 # analyse-imports
@@ -212,7 +212,9 @@ bootstrap-jsons: $(BOOTSTRAP_GHC_VERSIONS:%=bootstrap-json-%)
 ##############################################################################
 
 .PHONY: users-guide
-users-guide:
+users-guide: \
+  doc/ghc-syntax.rst \
+  doc/cabal-package-syntax.rst
 	$(MAKE) -C doc users-guide
 
 .PHONY: users-guide-requirements
diff --git a/buildinfo-reference-generator/buildinfo-reference-generator.cabal b/buildinfo-reference-generator/buildinfo-reference-generator.cabal
deleted file mode 100644
index 667e8346b63..00000000000
--- a/buildinfo-reference-generator/buildinfo-reference-generator.cabal
+++ /dev/null
@@ -1,16 +0,0 @@
-cabal-version: 2.2
-name:          buildinfo-reference-generator
-version:       0
-
-executable buildinfo-reference-generator
-  default-language: Haskell2010
-  hs-source-dirs:   src
-  ghc-options:      -Wall
-  main-is:          Main.hs
-  build-depends:
-    , base             >=4.11 && <4.20
-    , Cabal
-    , Cabal-described
-    , containers
-    , pretty
-    , zinza            ^>=0.2
diff --git a/buildinfo-reference-generator/src/Main.hs b/buildinfo-reference-generator/src/Main.hs
deleted file mode 100644
index dd0f01c8883..00000000000
--- a/buildinfo-reference-generator/src/Main.hs
+++ /dev/null
@@ -1,299 +0,0 @@
-{-# LANGUAGE DeriveFunctor         #-}
-{-# LANGUAGE DeriveGeneric         #-}
-{-# LANGUAGE MultiParamTypeClasses #-}
-module Main (main) where
-
-import Data.Map.Strict (Map)
-
-import Data.Bifunctor                  (first)
-import Data.Proxy                      (Proxy (..))
-import Data.Void                       (Void)
-import Distribution.CabalSpecVersion   (CabalSpecVersion, showCabalSpecVersion)
-import Distribution.Compat.Newtype     (pack')
-import Distribution.FieldGrammar.Class (FieldGrammar (..))
-import Distribution.Fields.Field       (FieldName)
-import Distribution.Pretty             (pretty)
-import Distribution.Simple.Utils       (fromUTF8BS)
-import GHC.Generics                    (Generic)
-import System.Environment              (getArgs)
-import System.Exit                     (exitFailure)
-
-import Distribution.PackageDescription.FieldGrammar (buildInfoFieldGrammar, packageDescriptionFieldGrammar, testSuiteFieldGrammar)
-
-import qualified Data.Map.Strict  as Map
-import qualified Text.PrettyPrint as PP
-
-import qualified Zinza as Z
-
-import Distribution.Described
-import Distribution.Described.Extension
-import Distribution.Utils.GrammarRegex
-
-import Distribution.ModuleName         (ModuleName)
-import Distribution.Types.Version      (Version)
-import Distribution.Types.VersionRange (VersionRange)
-
--------------------------------------------------------------------------------
--- Main
--------------------------------------------------------------------------------
-
-main :: IO ()
-main = do
-    args <- getArgs
-    case args of
-        [tmpl] -> do
-            -- TODO: getArgs
-            run <- Z.parseAndCompileTemplateIO tmpl
-            contents <- run $ Z
-                { zBuildInfoFields          = fromReference buildInfoFieldGrammar
-                , zPackageDescriptionFields = fromReference packageDescriptionFieldGrammar
-                , zTestSuiteFields          = fromReference $ testSuiteFieldGrammar // buildInfoFieldGrammar
-                , zProductions              =
-                    [ zproduction "interactive-extension" (reXs xGroupInteractive) "Language Extensions related to GHC interactive."
-                    , zproduction "phase-extension" (reXs xGroupPhase) "Language Extensions related to a particular GHC phase."
-                    , zproduction "syntax-extension" (reXs xGroupSyntax) "Syntax Language Extensions."
-                    , zproduction "import-export-extension" (reXs xGroupImportExport) "Import and Export Language Extensions."
-                    , zproduction "type-extension" (reXs xGroupTypes) "Language Extensions for Types."
-                    , zproduction "record-extension" (reXs xGroupRecords) "Record Language Extensions."
-                    , zproduction "deriving-extension" (reXs xGroupDeriving) "Language Extensions for deriving mechanisms."
-                    , zproduction "pattern-extension" (reXs xGroupPatterns) "Patterns Language Extensions."
-                    , zproduction "classes-instances-extension" (reXs xGroupClassesInstances) "Language Extensions for class and instance declarations."
-                    , zproduction "literal-extension" (reXs xGroupLiterals) "Literals Language Extensions."
-                    , zproduction "constraint-extension" (reXs xGroupConstraints) "Constraint Language Extensions."
-                    , zproduction "type-signature-extension" (reXs xGroupTypeSignatures) "Type Signature Language Extensions."
-                    , zproduction "binding-generalisation-extension" (reXs xGroupBindingsGeneralisation) "Language Extensions for bindings and generalisation "
-                    , zproduction "template-haskell-extension" (reXs xGroupTemplates) "Template Haskell Language Extensions."
-                    , zproduction "bang-strict-extension" (reXs xGroupBangStrict) "Bang pattern and Strict Haskell Language Extensions."
-                    , zproduction "parallel-concurrent-extension" (reXs xGroupParallelConcurrent) "Parallel and Concurrent Language Extensions."
-                    , zproduction "unboxed-primitive-extension" (reXs xGroupUnboxedPrimitive) "Unboxed types and Primitive operations Language Extensions."
-                    , zproduction "foreign-extension" (reXs xGroupForeign) "Foreign function interface (FFI) Language Extensions."
-                    , zproduction "safe-extension" (reXs xGroupSafe) "Safe Haskell Language Extensions."
-                    , zproduction "miscellaneous-extension" (reXs xGroupMiscellaneous) "Miscellaneous Language Extensions."
-                    , zproduction "bugs-extension" (reXs xGroupBugs) "Language Extensions related to GHC bugs and infelicities."
-                    , zproduction "ungrouped-extension" (reXs xUngrouped) "Language Extensions not belonging to other extension groups, includes undocumented extensions."
-                    , zproduction "enable-extension" reKnownExtension "GHC Language Extensions, some of these may be on by default."
-                    , zproduction "disable-extension" reDisableExtension "Disable a GHC Language Extension."
-                    , zproduction "hs-string"       reHsString
-                        "String as in Haskell; it's recommended to avoid using Haskell-specific escapes."
-                    , zproduction "unqual-name"     reUnqualComponent $ unwords
-                        [ "Unqualified component names are used for package names, component names etc. but not flag names."
-                        , "Unqualified component name consist of components separated by dash, each component is non-empty alphanumeric string, with at least one alphabetic character."
-                        , "In other words, component may not look like a number."
-                        ]
-
-                    , zproduction "module-name"     (describe (Proxy :: Proxy ModuleName))
-                        "Haskell module name as recognized by Cabal parser."
-                    , zproduction "version"         (describe (Proxy :: Proxy Version))
-                        "Version is to first approximation numbers separated by dots, where leading zero is not allowed and each version digit is consists at most of nine characters."
-                    , zproduction "version-range"   (describe (Proxy :: Proxy VersionRange))
-                        "Version range syntax is recursive. Also note the set syntax added in ``cabal-version: 3.0``, set cannot be empty."
-                    ]
-                , zSpaceList                = show $ regexDoc $
-                    REMunch RESpaces1 (RENamed "element" RETodo)
-                , zCommaList                = show $ regexDoc $
-                    expandedCommaList (RENamed "element" RETodo)
-                , zOptCommaList             = show $ regexDoc $
-                    expandedOptCommaList (RENamed "element" RETodo)
-
-                , zNull                     = null
-                , zNotNull                  = not . null
-                }
-
-            putStrLn contents
-        _ -> do
-          putStrLn "Usage: generator <tmpl>"
-          exitFailure
-
-zproduction :: String -> GrammarRegex Void -> String -> ZProduction
-zproduction name re desc = ZProduction
-    { zprodName        = name
-    , zprodSyntax      = show (regexDoc re')
-    , zprodDescription = desc
-    }
-  where
-    re' = case re of
-        RENamed _ r -> r
-        _           -> re
-
--- also in UnitTests.Distribution.Described
-expandedCommaList :: GrammarRegex a -> GrammarRegex a
-expandedCommaList = REUnion . expandedCommaList'
-
-expandedCommaList' :: GrammarRegex a -> [GrammarRegex a]
-expandedCommaList' r =
-    [ REMunch reSpacedComma r
-    , reComma <> RESpaces <> REMunch1 reSpacedComma r
-    , REMunch1 reSpacedComma r <> RESpaces <> reComma
-    ]
-
-expandedOptCommaList :: GrammarRegex a -> GrammarRegex a
-expandedOptCommaList r = REUnion $ reSpacedList r : expandedCommaList' r
-
--------------------------------------------------------------------------------
--- Template Inputs
--------------------------------------------------------------------------------
-
-data Z = Z
-    { zBuildInfoFields          :: [ZField]
-    , zPackageDescriptionFields :: [ZField]
-    , zTestSuiteFields          :: [ZField]
-    , zProductions              :: [ZProduction]
-    , zSpaceList                :: String
-    , zCommaList                :: String
-    , zOptCommaList             :: String
-    , zNull                     :: String -> Bool
-    , zNotNull                  :: String -> Bool
-    }
-  deriving (Generic)
-
-data ZField = ZField
-    { zfieldName            :: String
-    , zfieldAvailableSince  :: String
-    , zfieldDeprecatedSince :: (String, String)
-    , zfieldRemovedIn       :: (String, String)
-    , zfieldFormat          :: String
-    , zfieldDefault         :: String
-    , zfieldSyntax          :: String
-    }
-  deriving (Generic)
-
-data ZProduction = ZProduction
-    { zprodName        :: String
-    , zprodSyntax      :: String
-    , zprodDescription :: String
-    }
-  deriving (Generic)
-
-instance Z.Zinza Z where
-    toType    = Z.genericToTypeSFP
-    toValue   = Z.genericToValueSFP
-    fromValue = Z.genericFromValueSFP
-
-instance Z.Zinza ZField where
-    toType    = Z.genericToTypeSFP
-    toValue   = Z.genericToValueSFP
-    fromValue = Z.genericFromValueSFP
-
-instance Z.Zinza ZProduction where
-    toType    = Z.genericToTypeSFP
-    toValue   = Z.genericToValueSFP
-    fromValue = Z.genericFromValueSFP
-
--------------------------------------------------------------------------------
--- From reference
--------------------------------------------------------------------------------
-
--- TODO: produce ZField
-fromReference :: Reference a a -> [ZField]
-fromReference (Reference m) =
-    [ ZField
-        { zfieldName            = fromUTF8BS n
-        , zfieldAvailableSince  = maybe "" showCabalSpecVersion (fdAvailableSince desc)
-        , zfieldDeprecatedSince = maybe ("", "") (first showCabalSpecVersion) (fdDeprecatedSince desc)
-        , zfieldRemovedIn       = maybe ("", "") (first showCabalSpecVersion) (fdRemovedIn desc)
-        , zfieldFormat          = fmt
-        , zfieldDefault         = def
-        , zfieldSyntax          = syntax
-        }
-    | (n, desc) <- Map.toList m
-    , let (fmt, def, syntax) = fromFieldDesc' (fdDescription desc)
-    ]
-
-fromFieldDesc' :: FieldDesc' -> (String, String, String)
-fromFieldDesc' (MonoidalFieldAla s)        = ("Monoidal field",  "",       show s)
-fromFieldDesc' (BooleanFieldDesc def)      = ("Boolean field",   show def, show $ describeDoc ([] :: [Bool]))
-fromFieldDesc' (OptionalFieldAla s)        = ("Optional field",  "",       show s)
-fromFieldDesc' (OptionalFieldDefAla s def) = ("Optional field",  show def, show s)
-fromFieldDesc' FreeTextField               = ("Free text field", "",      "")
-fromFieldDesc' (UniqueField s)             = ("Required field",  "",       show s)
-
--------------------------------------------------------------------------------
--- Reference
--------------------------------------------------------------------------------
-
-newtype Reference a b = Reference (Map FieldName FieldDesc)
-  deriving (Functor)
-
-referenceAvailableSince :: CabalSpecVersion -> Reference a b -> Reference a b
-referenceAvailableSince v (Reference m) =
-    Reference (fmap (fieldDescAvailableSince v) m)
-
-referenceRemovedIn :: CabalSpecVersion -> String -> Reference a b -> Reference a b
-referenceRemovedIn v desc (Reference m) =
-    Reference (fmap (fieldDescRemovedIn v desc) m)
-
-referenceDeprecatedSince :: CabalSpecVersion -> String -> Reference a b -> Reference a b
-referenceDeprecatedSince v desc (Reference m) =
-    Reference (fmap (fieldDescDeprecatedSince v desc) m)
-
-(//) :: Reference a b -> Reference c d -> Reference a b
-Reference ab // Reference cd = Reference $ Map.difference ab cd
-
-fieldDescAvailableSince :: CabalSpecVersion -> FieldDesc -> FieldDesc
-fieldDescAvailableSince v d = d { fdAvailableSince = Just v }
-
-fieldDescRemovedIn :: CabalSpecVersion -> String -> FieldDesc -> FieldDesc
-fieldDescRemovedIn v desc d = d { fdRemovedIn = Just (v, desc) }
-
-fieldDescDeprecatedSince :: CabalSpecVersion -> String -> FieldDesc -> FieldDesc
-fieldDescDeprecatedSince v desc d = d { fdDeprecatedSince = Just (v, desc) }
-
-data FieldDesc = FieldDesc
-    { fdAvailableSince  :: Maybe CabalSpecVersion
-    , fdRemovedIn       :: Maybe (CabalSpecVersion, String)
-    , fdDeprecatedSince :: Maybe (CabalSpecVersion, String)
-    , fdDescription     :: FieldDesc'
-    }
-  deriving Show
-
-reference :: FieldName -> FieldDesc' -> Reference a b
-reference fn d = Reference $ Map.singleton fn $ FieldDesc Nothing Nothing Nothing d
-
-data FieldDesc'
-    = BooleanFieldDesc Bool
-    | UniqueField  PP.Doc  -- ^ not used in BuildInfo
-    | FreeTextField        -- ^ not user in BuildInfo
-    | OptionalFieldAla PP.Doc
-    | OptionalFieldDefAla PP.Doc PP.Doc
-    | MonoidalFieldAla PP.Doc
-  deriving Show
-
-instance Applicative (Reference a) where
-    pure _                      = Reference Map.empty
-    Reference f <*> Reference x = Reference (Map.union f x)
-
-instance FieldGrammar Described Reference where
-    blurFieldGrammar _ (Reference xs) = Reference xs
-
-    uniqueFieldAla fn pack _l =
-        reference fn $ UniqueField (describeDoc pack)
-
-    booleanFieldDef fn _l def =
-        reference fn $ BooleanFieldDesc def
-
-    optionalFieldAla fn pack _l =
-        reference fn $ OptionalFieldAla (describeDoc pack)
-
-    optionalFieldDefAla fn pack _l def =
-        reference fn $ OptionalFieldDefAla
-            (describeDoc pack)
-            (pretty $ pack' pack def)
-
-    freeTextField fn _l = reference fn FreeTextField
-
-    freeTextFieldDef   fn _l = reference fn FreeTextField
-    freeTextFieldDefST fn _l = reference fn FreeTextField
-
-    monoidalFieldAla fn pack _l =
-        reference fn (MonoidalFieldAla (describeDoc pack))
-
-    prefixedFields _pfx _l = Reference Map.empty
-
-    knownField _fn = Reference Map.empty -- TODO
-
-    -- hidden fields are hidden from the reference.
-    hiddenField _ = Reference Map.empty
-
-    deprecatedSince = referenceDeprecatedSince
-    removedIn       = referenceRemovedIn
-    availableSince  v _ r = referenceAvailableSince v r
diff --git a/cabal.project.buildinfo b/cabal.project.docs
similarity index 63%
rename from cabal.project.buildinfo
rename to cabal.project.docs
index 839f35c5805..d59cf4a3f16 100644
--- a/cabal.project.buildinfo
+++ b/cabal.project.docs
@@ -1,7 +1,7 @@
-packages: Cabal-syntax/
-packages: Cabal/
+packages: Cabal-syntax
+packages: Cabal
 packages: Cabal-described
-packages: buildinfo-reference-generator/
+packages: Cabal-syntax-docs
 tests: False
 optimization: False
 
diff --git a/doc/buildinfo-fields-reference.rst b/doc/cabal-package-syntax.rst
similarity index 67%
rename from doc/buildinfo-fields-reference.rst
rename to doc/cabal-package-syntax.rst
index f34486cb7ce..7e3ba57ae2a 100644
--- a/doc/buildinfo-fields-reference.rst
+++ b/doc/cabal-package-syntax.rst
@@ -1,10 +1,26 @@
-.. _buildinfo-field-reference:
+.. _cabal-package-syntax:
 
-Field Syntax Reference
-======================
+Cabal Package Syntax
+====================
+
+GHC syntax
+----------
+
+Some elements of cabal package syntax are controlled by GHC. As such these are
+effectively strings passed on to GHC and that may be as far as Cabal will check
+their syntax. See the :ref:`ghc-syntax` for these elements of GHC syntax
+embedded within cabal package descriptions.
+
+- :ref:`ghc-enable-extension`
+- :ref:`ghc-disable-extension`
+- :ref:`default-extensions<ghc-default-extensions>`
+- :ref:`default-language<ghc-default-language>`
+- :ref:`extensions<ghc-extensions>`
+- :ref:`other-extensions<ghc-other-extensions>`
+- :ref:`other-languages<ghc-other-languages>`
 
 Notation
----------------
+--------
 
 Field syntax is described as they are in the latest cabal file format version.
 
@@ -129,174 +145,6 @@ Non-terminals
 
 In the syntax definitions below the following non-terminal symbols are used:
 
-interactive-extension
-    Language Extensions related to GHC interactive.
-
-    .. math::
-
-        \mathop{\mathord{``}\mathtt{ExtendedDefaultRules}\mathord{"}}
-
-phase-extension
-    Language Extensions related to a particular GHC phase.
-
-    .. math::
-
-        \mathop{\mathord{``}\mathtt{CPP}\mathord{"}}
-
-syntax-extension
-    Syntax Language Extensions.
-
-    .. math::
-
-        \left\{ \begin{gathered}\mathop{\mathord{``}\mathtt{UnicodeSyntax}\mathord{"}}\\\mathop{\mathord{``}\mathtt{MagicHash}\mathord{"}}\\\mathop{\mathord{``}\mathtt{RecursiveDo}\mathord{"}}\\\mathop{\mathord{``}\mathtt{ApplicativeDo}\mathord{"}}\\\mathop{\mathord{``}\mathtt{QualifiedDo}\mathord{"}}\\\mathop{\mathord{``}\mathtt{ParallelListComp}\mathord{"}}\\\mathop{\mathord{``}\mathtt{TransformListComp}\mathord{"}}\\\mathop{\mathord{``}\mathtt{MonadComprehensions}\mathord{"}}\\\mathop{\mathord{``}\mathtt{OverloadedLists}\mathord{"}}\\\mathop{\mathord{``}\mathtt{ImplicitPrelude}\mathord{"}}\\\mathop{\mathord{``}\mathtt{RebindableSyntax}\mathord{"}}\\\mathop{\mathord{``}\mathtt{PostfixOperators}\mathord{"}}\\\mathop{\mathord{``}\mathtt{TupleSections}\mathord{"}}\\\mathop{\mathord{``}\mathtt{LambdaCase}\mathord{"}}\\\mathop{\mathord{``}\mathtt{EmptyCase}\mathord{"}}\\\mathop{\mathord{``}\mathtt{MultiWayIf}\mathord{"}}\\\mathop{\mathord{``}\mathtt{Arrows}\mathord{"}}\\\mathop{\mathord{``}\mathtt{LexicalNegation}\mathord{"}}\\\mathop{\mathord{``}\mathtt{BlockArguments}\mathord{"}}\end{gathered} \right\}
-
-import-export-extension
-    Import and Export Language Extensions.
-
-    .. math::
-
-        \left\{ \mathop{\mathord{``}\mathtt{PackageImports}\mathord{"}}\mid\mathop{\mathord{``}\mathtt{ExplicitNamespaces}\mathord{"}}\mid\mathop{\mathord{``}\mathtt{ImportQualifiedPost}\mathord{"}} \right\}
-
-type-extension
-    Language Extensions for Types.
-
-    .. math::
-
-        \left\{ \begin{gathered}\mathop{\mathord{``}\mathtt{EmptyDataDecls}\mathord{"}}\\\mathop{\mathord{``}\mathtt{DatatypeContexts}\mathord{"}}\\\mathop{\mathord{``}\mathtt{TypeOperators}\mathord{"}}\\\mathop{\mathord{``}\mathtt{LiberalTypeSynonyms}\mathord{"}}\\\mathop{\mathord{``}\mathtt{ExistentialQuantification}\mathord{"}}\\\mathop{\mathord{``}\mathtt{GADTSyntax}\mathord{"}}\\\mathop{\mathord{``}\mathtt{GADTs}\mathord{"}}\\\mathop{\mathord{``}\mathtt{TypeFamilies}\mathord{"}}\\\mathop{\mathord{``}\mathtt{TypeFamilyDependencies}\mathord{"}}\\\mathop{\mathord{``}\mathtt{DataKinds}\mathord{"}}\\\mathop{\mathord{``}\mathtt{TypeData}\mathord{"}}\\\mathop{\mathord{``}\mathtt{TypeInType}\mathord{"}}\\\mathop{\mathord{``}\mathtt{PolyKinds}\mathord{"}}\\\mathop{\mathord{``}\mathtt{CUSKs}\mathord{"}}\\\mathop{\mathord{``}\mathtt{StandaloneKindSignatures}\mathord{"}}\\\mathop{\mathord{``}\mathtt{StarIsType}\mathord{"}}\\\mathop{\mathord{``}\mathtt{TypeApplications}\mathord{"}}\\\mathop{\mathord{``}\mathtt{TypeAbstractions}\mathord{"}}\\\mathop{\mathord{``}\mathtt{RequiredTypeArguments}\mathord{"}}\\\mathop{\mathord{``}\mathtt{RankNTypes}\mathord{"}}\\\mathop{\mathord{``}\mathtt{Rank2Types}\mathord{"}}\\\mathop{\mathord{``}\mathtt{DeepSubsumption}\mathord{"}}\\\mathop{\mathord{``}\mathtt{ImpredicativeTypes}\mathord{"}}\\\mathop{\mathord{``}\mathtt{LinearTypes}\mathord{"}}\\\mathop{\mathord{``}\mathtt{RoleAnnotations}\mathord{"}}\end{gathered} \right\}
-
-record-extension
-    Record Language Extensions.
-
-    .. math::
-
-        \left\{ \begin{gathered}\mathop{\mathord{``}\mathtt{TraditionalRecordSyntax}\mathord{"}}\\\mathop{\mathord{``}\mathtt{DisambiguateRecordFields}\mathord{"}}\\\mathop{\mathord{``}\mathtt{DuplicateRecordFields}\mathord{"}}\\\mathop{\mathord{``}\mathtt{FieldSelectors}\mathord{"}}\\\mathop{\mathord{``}\mathtt{NamedFieldPuns}\mathord{"}}\\\mathop{\mathord{``}\mathtt{RecordWildCards}\mathord{"}}\\\mathop{\mathord{``}\mathtt{OverloadedRecordDot}\mathord{"}}\\\mathop{\mathord{``}\mathtt{OverloadedRecordUpdate}\mathord{"}}\end{gathered} \right\}
-
-deriving-extension
-    Language Extensions for deriving mechanisms.
-
-    .. math::
-
-        \left\{ \begin{gathered}\mathop{\mathord{``}\mathtt{EmptyDataDeriving}\mathord{"}}\\\mathop{\mathord{``}\mathtt{StandaloneDeriving}\mathord{"}}\\\mathop{\mathord{``}\mathtt{DeriveFoldable}\mathord{"}}\\\mathop{\mathord{``}\mathtt{DeriveFunctor}\mathord{"}}\\\mathop{\mathord{``}\mathtt{DeriveTraversable}\mathord{"}}\\\mathop{\mathord{``}\mathtt{DeriveDataTypeable}\mathord{"}}\\\mathop{\mathord{``}\mathtt{DeriveLift}\mathord{"}}\\\mathop{\mathord{``}\mathtt{GeneralizedNewtypeDeriving}\mathord{"}}\\\mathop{\mathord{``}\mathtt{GeneralisedNewtypeDeriving}\mathord{"}}\\\mathop{\mathord{``}\mathtt{DeriveAnyClass}\mathord{"}}\\\mathop{\mathord{``}\mathtt{DerivingStrategies}\mathord{"}}\\\mathop{\mathord{``}\mathtt{DerivingVia}\mathord{"}}\end{gathered} \right\}
-
-pattern-extension
-    Patterns Language Extensions.
-
-    .. math::
-
-        \left\{ \begin{gathered}\mathop{\mathord{``}\mathtt{PatternGuards}\mathord{"}}\\\mathop{\mathord{``}\mathtt{ViewPatterns}\mathord{"}}\\\mathop{\mathord{``}\mathtt{NPlusKPatterns}\mathord{"}}\\\mathop{\mathord{``}\mathtt{PatternSynonyms}\mathord{"}}\end{gathered} \right\}
-
-classes-instances-extension
-    Language Extensions for class and instance declarations.
-
-    .. math::
-
-        \left\{ \begin{gathered}\mathop{\mathord{``}\mathtt{MultiParamTypeClasses}\mathord{"}}\\\mathop{\mathord{``}\mathtt{UndecidableSuperClasses}\mathord{"}}\\\mathop{\mathord{``}\mathtt{ConstrainedClassMethods}\mathord{"}}\\\mathop{\mathord{``}\mathtt{DefaultSignatures}\mathord{"}}\\\mathop{\mathord{``}\mathtt{NullaryTypeClasses}\mathord{"}}\\\mathop{\mathord{``}\mathtt{FunctionalDependencies}\mathord{"}}\\\mathop{\mathord{``}\mathtt{TypeSynonymInstances}\mathord{"}}\\\mathop{\mathord{``}\mathtt{FlexibleInstances}\mathord{"}}\\\mathop{\mathord{``}\mathtt{UndecidableInstances}\mathord{"}}\\\mathop{\mathord{``}\mathtt{OverlappingInstances}\mathord{"}}\\\mathop{\mathord{``}\mathtt{IncoherentInstances}\mathord{"}}\\\mathop{\mathord{``}\mathtt{InstanceSigs}\mathord{"}}\end{gathered} \right\}
-
-literal-extension
-    Literals Language Extensions.
-
-    .. math::
-
-        \left\{ \begin{gathered}\mathop{\mathord{``}\mathtt{NegativeLiterals}\mathord{"}}\\\mathop{\mathord{``}\mathtt{BinaryLiterals}\mathord{"}}\\\mathop{\mathord{``}\mathtt{HexFloatLiterals}\mathord{"}}\\\mathop{\mathord{``}\mathtt{NumDecimals}\mathord{"}}\\\mathop{\mathord{``}\mathtt{ExtendedLiterals}\mathord{"}}\\\mathop{\mathord{``}\mathtt{NumericUnderscores}\mathord{"}}\\\mathop{\mathord{``}\mathtt{OverloadedStrings}\mathord{"}}\\\mathop{\mathord{``}\mathtt{OverloadedLabels}\mathord{"}}\end{gathered} \right\}
-
-constraint-extension
-    Constraint Language Extensions.
-
-    .. math::
-
-        \left\{ \mathop{\mathord{``}\mathtt{FlexibleContexts}\mathord{"}}\mid\mathop{\mathord{``}\mathtt{ConstraintKinds}\mathord{"}}\mid\mathop{\mathord{``}\mathtt{QuantifiedConstraints}\mathord{"}} \right\}
-
-type-signature-extension
-    Type Signature Language Extensions.
-
-    .. math::
-
-        \left\{ \begin{gathered}\mathop{\mathord{``}\mathtt{ExplicitForAll}\mathord{"}}\\\mathop{\mathord{``}\mathtt{AllowAmbiguousTypes}\mathord{"}}\\\mathop{\mathord{``}\mathtt{KindSignatures}\mathord{"}}\\\mathop{\mathord{``}\mathtt{ScopedTypeVariables}\mathord{"}}\\\mathop{\mathord{``}\mathtt{ImplicitParams}\mathord{"}}\\\mathop{\mathord{``}\mathtt{PartialTypeSignatures}\mathord{"}}\\\mathop{\mathord{``}\mathtt{NamedWildCards}\mathord{"}}\end{gathered} \right\}
-
-binding-generalisation-extension
-    Language Extensions for bindings and generalisation 
-
-    .. math::
-
-        \left\{ \mathop{\mathord{``}\mathtt{MonomorphismRestriction}\mathord{"}}\mid\mathop{\mathord{``}\mathtt{MonoLocalBinds}\mathord{"}} \right\}
-
-template-haskell-extension
-    Template Haskell Language Extensions.
-
-    .. math::
-
-        \left\{ \mathop{\mathord{``}\mathtt{TemplateHaskell}\mathord{"}}\mid\mathop{\mathord{``}\mathtt{TemplateHaskellQuotes}\mathord{"}}\mid\mathop{\mathord{``}\mathtt{QuasiQuotes}\mathord{"}} \right\}
-
-bang-strict-extension
-    Bang pattern and Strict Haskell Language Extensions.
-
-    .. math::
-
-        \left\{ \mathop{\mathord{``}\mathtt{BangPatterns}\mathord{"}}\mid\mathop{\mathord{``}\mathtt{StrictData}\mathord{"}}\mid\mathop{\mathord{``}\mathtt{Strict}\mathord{"}} \right\}
-
-parallel-concurrent-extension
-    Parallel and Concurrent Language Extensions.
-
-    .. math::
-
-        \mathop{\mathord{``}\mathtt{StaticPointers}\mathord{"}}
-
-unboxed-primitive-extension
-    Unboxed types and Primitive operations Language Extensions.
-
-    .. math::
-
-        \left\{ \begin{gathered}\mathop{\mathord{``}\mathtt{UnboxedTuples}\mathord{"}}\\\mathop{\mathord{``}\mathtt{UnboxedSums}\mathord{"}}\\\mathop{\mathord{``}\mathtt{UnliftedNewtypes}\mathord{"}}\\\mathop{\mathord{``}\mathtt{UnliftedDatatypes}\mathord{"}}\end{gathered} \right\}
-
-foreign-extension
-    Foreign function interface (FFI) Language Extensions.
-
-    .. math::
-
-        \left\{ \begin{gathered}\mathop{\mathord{``}\mathtt{ForeignFunctionInterface}\mathord{"}}\\\mathop{\mathord{``}\mathtt{UnliftedFFITypes}\mathord{"}}\\\mathop{\mathord{``}\mathtt{GHCForeignImportPrim}\mathord{"}}\\\mathop{\mathord{``}\mathtt{InterruptibleFFI}\mathord{"}}\\\mathop{\mathord{``}\mathtt{CApiFFI}\mathord{"}}\end{gathered} \right\}
-
-safe-extension
-    Safe Haskell Language Extensions.
-
-    .. math::
-
-        \left\{ \mathop{\mathord{``}\mathtt{Safe}\mathord{"}}\mid\mathop{\mathord{``}\mathtt{Trustworthy}\mathord{"}}\mid\mathop{\mathord{``}\mathtt{Unsafe}\mathord{"}} \right\}
-
-miscellaneous-extension
-    Miscellaneous Language Extensions.
-
-    .. math::
-
-        \mathop{\mathord{``}\mathtt{DeriveGeneric}\mathord{"}}
-
-bugs-extension
-    Language Extensions related to GHC bugs and infelicities.
-
-    .. math::
-
-        \mathop{\mathord{``}\mathtt{NondecreasingIndentation}\mathord{"}}
-
-ungrouped-extension
-    Language Extensions not belonging to other extension groups, includes undocumented extensions.
-
-    .. math::
-
-        \left\{ \begin{gathered}\mathop{\mathord{``}\mathtt{DoRec}\mathord{"}}\\\mathop{\mathord{``}\mathtt{PolymorphicComponents}\mathord{"}}\\\mathop{\mathord{``}\mathtt{PatternSignatures}\mathord{"}}\\\mathop{\mathord{``}\mathtt{Generics}\mathord{"}}\\\mathop{\mathord{``}\mathtt{ExtensibleRecords}\mathord{"}}\\\mathop{\mathord{``}\mathtt{RestrictedTypeSynonyms}\mathord{"}}\\\mathop{\mathord{``}\mathtt{HereDocuments}\mathord{"}}\\\mathop{\mathord{``}\mathtt{RecordPuns}\mathord{"}}\\\mathop{\mathord{``}\mathtt{MonoPatBinds}\mathord{"}}\\\mathop{\mathord{``}\mathtt{RelaxedPolyRec}\mathord{"}}\\\mathop{\mathord{``}\mathtt{NewQualifiedOperators}\mathord{"}}\\\mathop{\mathord{``}\mathtt{XmlSyntax}\mathord{"}}\\\mathop{\mathord{``}\mathtt{RegularPatterns}\mathord{"}}\\\mathop{\mathord{``}\mathtt{DoAndIfThenElse}\mathord{"}}\\\mathop{\mathord{``}\mathtt{SafeImports}\mathord{"}}\\\mathop{\mathord{``}\mathtt{ParallelArrays}\mathord{"}}\\\mathop{\mathord{``}\mathtt{AutoDeriveTypeable}\mathord{"}}\\\mathop{\mathord{``}\mathtt{JavaScriptFFI}\mathord{"}}\\\mathop{\mathord{``}\mathtt{MonadFailDesugaring}\mathord{"}}\\\mathop{\mathord{``}\mathtt{AlternativeLayoutRule}\mathord{"}}\\\mathop{\mathord{``}\mathtt{AlternativeLayoutRuleTransitional}\mathord{"}}\\\mathop{\mathord{``}\mathtt{RelaxedLayout}\mathord{"}}\end{gathered} \right\}
-
-enable-extension
-    GHC Language Extensions, some of these may be on by default.
-
-    .. math::
-
-        \left\{ \begin{gathered}\mathop{\mathit{interactive\text{-}extension}}\\\mathop{\mathit{phase\text{-}extension}}\\\mathop{\mathit{syntax\text{-}extension}}\\\mathop{\mathit{import\text{-}export\text{-}extension}}\\\mathop{\mathit{type\text{-}extension}}\\\mathop{\mathit{record\text{-}extension}}\\\mathop{\mathit{deriving\text{-}extension}}\\\mathop{\mathit{pattern\text{-}extension}}\\\mathop{\mathit{classes\text{-}instances\text{-}extension}}\\\mathop{\mathit{literals\text{-}extension}}\\\mathop{\mathit{constraint\text{-}extension}}\\\mathop{\mathit{type\text{-}signature\text{-}extension}}\\\mathop{\mathit{binding\text{-}generalisation\text{-}extension}}\\\mathop{\mathit{template\text{-}haskell\text{-}extension}}\\\mathop{\mathit{bang\text{-}strict\text{-}extension}}\\\mathop{\mathit{parallel\text{-}concurrent\text{-}extension}}\\\mathop{\mathit{unboxed\text{-}primitive\text{-}extension}}\\\mathop{\mathit{foreign\text{-}extension}}\\\mathop{\mathit{safe\text{-}extension}}\\\mathop{\mathit{miscellaneous\text{-}extension}}\\\mathop{\mathit{bugs\text{-}extension}}\\\mathop{\mathit{ungrouped\text{-}extension}}\end{gathered} \right\}
-
-disable-extension
-    Disable a GHC Language Extension.
-
-    .. math::
-
-        \mathop{\mathord{``}\mathtt{No}\mathord{"}}\mathop{\mathit{enable\text{-}extension}}
-
 hs-string
     String as in Haskell; it's recommended to avoid using Haskell-specific escapes.
 
@@ -466,33 +314,6 @@ cxx-sources
 
         \mathrm{commalist}\left\{ \mathop{\mathit{hs\text{-}string}}\mid{{[\mathop{\mathord{``}\mathtt{\ }\mathord{"}}\mathop{\mathord{``}\mathtt{\text{,}}\mathord{"}}]^c}}^+_{} \right\}
 
-default-extensions
-    * Monoidal field
-    * Available since ``cabal-version: 1.10``.
-    * Documentation of :pkg-field:`library:default-extensions`
-
-    .. math::
-
-        \mathrm{optcommalist}\left\{ \mathop{\mathit{enable\text{-}extension}}\mid\mathop{\mathit{disable\text{-}extension}} \right\}
-
-default-language
-    * Optional field
-    * Available since ``cabal-version: 1.10``.
-    * Documentation of :pkg-field:`library:default-language`
-
-    .. math::
-
-        \left\{ \mathop{\mathord{``}\mathtt{GHC2021}\mathord{"}}\mid\mathop{\mathord{``}\mathtt{Haskell2010}\mathord{"}}\mid\mathop{\mathord{``}\mathtt{Haskell98}\mathord{"}} \right\}
-
-extensions
-    * Monoidal field
-    * Deprecated since ``cabal-version: 1.12``: Please use 'default-extensions' or 'other-extensions' fields.
-    * Removed in ``cabal-version: 3.0``: Please use 'default-extensions' or 'other-extensions' fields.
-
-    .. math::
-
-        \mathrm{optcommalist}\left\{ \mathop{\mathit{enable\text{-}extension}}\mid\mathop{\mathit{disable\text{-}extension}} \right\}
-
 extra-bundled-libraries
     * Monoidal field
     * Documentation of :pkg-field:`library:extra-bundled-libraries`
@@ -699,23 +520,6 @@ mixins
 
         \mathrm{commalist}\left(\mathop{\mathit{package\text{-}name}}{\left(\mathop{\mathord{``}\mathtt{\text{:}}\mathord{"}}\mathop{\mathit{library\text{-}name}}\right)}^?{\left(\bullet\left\{ \mid\mathop{\mathord{``}\mathtt{hiding}\mathord{"}}\circ\mathop{\mathord{``}\mathtt{\text{(}}\mathord{"}}\circ{\mathop{\mathit{module\text{-}name}}}^\ast_{\left(\circ\mathop{\mathord{``}\mathtt{\text{,}}\mathord{"}}\circ\right)}\circ\mathop{\mathord{``}\mathtt{\text{)}}\mathord{"}}\mid\mathop{\mathord{``}\mathtt{\text{(}}\mathord{"}}\circ{\left(\mathop{\mathit{module\text{-}name}}{\left(\bullet\mathop{\mathord{``}\mathtt{as}\mathord{"}}\bullet\mathop{\mathit{module\text{-}name}}\right)}^?\right)}^\ast_{\left(\circ\mathop{\mathord{``}\mathtt{\text{,}}\mathord{"}}\circ\right)}\circ\mathop{\mathord{``}\mathtt{\text{)}}\mathord{"}} \right\}{\left(\circ\mathop{\mathord{``}\mathtt{requires}\mathord{"}}\bullet\left\{ \mid\mathop{\mathord{``}\mathtt{hiding}\mathord{"}}\circ\mathop{\mathord{``}\mathtt{\text{(}}\mathord{"}}\circ{\mathop{\mathit{module\text{-}name}}}^\ast_{\left(\circ\mathop{\mathord{``}\mathtt{\text{,}}\mathord{"}}\circ\right)}\circ\mathop{\mathord{``}\mathtt{\text{)}}\mathord{"}}\mid\mathop{\mathord{``}\mathtt{\text{(}}\mathord{"}}\circ{\left(\mathop{\mathit{module\text{-}name}}{\left(\bullet\mathop{\mathord{``}\mathtt{as}\mathord{"}}\bullet\mathop{\mathit{module\text{-}name}}\right)}^?\right)}^\ast_{\left(\circ\mathop{\mathord{``}\mathtt{\text{,}}\mathord{"}}\circ\right)}\circ\mathop{\mathord{``}\mathtt{\text{)}}\mathord{"}} \right\}\right)}^?\right)}^?\right)
 
-other-extensions
-    * Monoidal field
-    * Documentation of :pkg-field:`library:other-extensions`
-
-    .. math::
-
-        \mathrm{optcommalist}\left\{ \mathop{\mathit{enable\text{-}extension}}\mid\mathop{\mathit{disable\text{-}extension}} \right\}
-
-other-languages
-    * Monoidal field
-    * Available since ``cabal-version: 1.10``.
-    * Documentation of :pkg-field:`library:other-languages`
-
-    .. math::
-
-        \mathrm{optcommalist}\left\{ \mathop{\mathord{``}\mathtt{GHC2021}\mathord{"}}\mid\mathop{\mathord{``}\mathtt{Haskell2010}\mathord{"}}\mid\mathop{\mathord{``}\mathtt{Haskell98}\mathord{"}} \right\}
-
 other-modules
     * Monoidal field
     * Documentation of :pkg-field:`library:other-modules`
diff --git a/doc/ghc-syntax.rst b/doc/ghc-syntax.rst
new file mode 100644
index 00000000000..3e5601e1e39
--- /dev/null
+++ b/doc/ghc-syntax.rst
@@ -0,0 +1,292 @@
+.. _ghc-syntax:
+
+GHC Syntax Reference
+====================
+
+Language Extensions
+-------------------
+
+The many GHC language extensions are divided into groups of extensions
+corresponding to subsections of the GHC users' guide on language extensions.
+Those of the :ref:`ungrouped-extension <ghc-ungrouped-extension>` group are
+undocumented in the GHC users' guide.
+
+.. _ghc-disable-extension:
+
+disable-extension
+    Disable a language extension by prepending the extension with "No".
+
+    .. math::
+
+        \mathop{\mathord{``}\mathtt{No}\mathord{"}}\mathop{\mathit{enable\text{-}extension}}
+
+.. _ghc-enable-extension:
+
+enable-extension
+    All GHC language extensions known to cabal. There may be more and some of these may be on by default.
+
+    .. math::
+
+        \left\{ \begin{gathered}\mathop{\mathit{interactive\text{-}extension}}\\\mathop{\mathit{phase\text{-}extension}}\\\mathop{\mathit{syntax\text{-}extension}}\\\mathop{\mathit{import\text{-}export\text{-}extension}}\\\mathop{\mathit{type\text{-}extension}}\\\mathop{\mathit{record\text{-}extension}}\\\mathop{\mathit{deriving\text{-}extension}}\\\mathop{\mathit{pattern\text{-}extension}}\\\mathop{\mathit{classes\text{-}instances\text{-}extension}}\\\mathop{\mathit{literals\text{-}extension}}\\\mathop{\mathit{constraint\text{-}extension}}\\\mathop{\mathit{type\text{-}signature\text{-}extension}}\\\mathop{\mathit{binding\text{-}generalisation\text{-}extension}}\\\mathop{\mathit{template\text{-}haskell\text{-}extension}}\\\mathop{\mathit{bang\text{-}strict\text{-}extension}}\\\mathop{\mathit{parallel\text{-}concurrent\text{-}extension}}\\\mathop{\mathit{unboxed\text{-}primitive\text{-}extension}}\\\mathop{\mathit{foreign\text{-}extension}}\\\mathop{\mathit{safe\text{-}extension}}\\\mathop{\mathit{miscellaneous\text{-}extension}}\\\mathop{\mathit{bugs\text{-}extension}}\\\mathop{\mathit{ungrouped\text{-}extension}}\end{gathered} \right\}
+
+.. _ghc-interactive-extension:
+
+interactive-extension
+    Language Extensions related to GHC interactive.
+
+    .. math::
+
+        \mathop{\mathord{``}\mathtt{ExtendedDefaultRules}\mathord{"}}
+
+.. _ghc-phase-extension:
+
+phase-extension
+    Language Extensions related to a particular GHC phase.
+
+    .. math::
+
+        \mathop{\mathord{``}\mathtt{CPP}\mathord{"}}
+
+.. _ghc-syntax-extension:
+
+syntax-extension
+    Syntax Language Extensions.
+
+    .. math::
+
+        \left\{ \begin{gathered}\mathop{\mathord{``}\mathtt{UnicodeSyntax}\mathord{"}}\\\mathop{\mathord{``}\mathtt{MagicHash}\mathord{"}}\\\mathop{\mathord{``}\mathtt{RecursiveDo}\mathord{"}}\\\mathop{\mathord{``}\mathtt{ApplicativeDo}\mathord{"}}\\\mathop{\mathord{``}\mathtt{QualifiedDo}\mathord{"}}\\\mathop{\mathord{``}\mathtt{ParallelListComp}\mathord{"}}\\\mathop{\mathord{``}\mathtt{TransformListComp}\mathord{"}}\\\mathop{\mathord{``}\mathtt{MonadComprehensions}\mathord{"}}\\\mathop{\mathord{``}\mathtt{OverloadedLists}\mathord{"}}\\\mathop{\mathord{``}\mathtt{ImplicitPrelude}\mathord{"}}\\\mathop{\mathord{``}\mathtt{RebindableSyntax}\mathord{"}}\\\mathop{\mathord{``}\mathtt{PostfixOperators}\mathord{"}}\\\mathop{\mathord{``}\mathtt{TupleSections}\mathord{"}}\\\mathop{\mathord{``}\mathtt{LambdaCase}\mathord{"}}\\\mathop{\mathord{``}\mathtt{EmptyCase}\mathord{"}}\\\mathop{\mathord{``}\mathtt{MultiWayIf}\mathord{"}}\\\mathop{\mathord{``}\mathtt{Arrows}\mathord{"}}\\\mathop{\mathord{``}\mathtt{LexicalNegation}\mathord{"}}\\\mathop{\mathord{``}\mathtt{BlockArguments}\mathord{"}}\end{gathered} \right\}
+
+.. _ghc-import-export-extension:
+
+import-export-extension
+    Import and Export Language Extensions.
+
+    .. math::
+
+        \left\{ \mathop{\mathord{``}\mathtt{PackageImports}\mathord{"}}\mid\mathop{\mathord{``}\mathtt{ExplicitNamespaces}\mathord{"}}\mid\mathop{\mathord{``}\mathtt{ImportQualifiedPost}\mathord{"}} \right\}
+
+.. _ghc-type-extension:
+
+type-extension
+    Language Extensions for Types.
+
+    .. math::
+
+        \left\{ \begin{gathered}\mathop{\mathord{``}\mathtt{EmptyDataDecls}\mathord{"}}\\\mathop{\mathord{``}\mathtt{DatatypeContexts}\mathord{"}}\\\mathop{\mathord{``}\mathtt{TypeOperators}\mathord{"}}\\\mathop{\mathord{``}\mathtt{LiberalTypeSynonyms}\mathord{"}}\\\mathop{\mathord{``}\mathtt{ExistentialQuantification}\mathord{"}}\\\mathop{\mathord{``}\mathtt{GADTSyntax}\mathord{"}}\\\mathop{\mathord{``}\mathtt{GADTs}\mathord{"}}\\\mathop{\mathord{``}\mathtt{TypeFamilies}\mathord{"}}\\\mathop{\mathord{``}\mathtt{TypeFamilyDependencies}\mathord{"}}\\\mathop{\mathord{``}\mathtt{DataKinds}\mathord{"}}\\\mathop{\mathord{``}\mathtt{TypeData}\mathord{"}}\\\mathop{\mathord{``}\mathtt{TypeInType}\mathord{"}}\\\mathop{\mathord{``}\mathtt{PolyKinds}\mathord{"}}\\\mathop{\mathord{``}\mathtt{CUSKs}\mathord{"}}\\\mathop{\mathord{``}\mathtt{StandaloneKindSignatures}\mathord{"}}\\\mathop{\mathord{``}\mathtt{StarIsType}\mathord{"}}\\\mathop{\mathord{``}\mathtt{TypeApplications}\mathord{"}}\\\mathop{\mathord{``}\mathtt{TypeAbstractions}\mathord{"}}\\\mathop{\mathord{``}\mathtt{RequiredTypeArguments}\mathord{"}}\\\mathop{\mathord{``}\mathtt{RankNTypes}\mathord{"}}\\\mathop{\mathord{``}\mathtt{Rank2Types}\mathord{"}}\\\mathop{\mathord{``}\mathtt{DeepSubsumption}\mathord{"}}\\\mathop{\mathord{``}\mathtt{ImpredicativeTypes}\mathord{"}}\\\mathop{\mathord{``}\mathtt{LinearTypes}\mathord{"}}\\\mathop{\mathord{``}\mathtt{RoleAnnotations}\mathord{"}}\end{gathered} \right\}
+
+.. _ghc-record-extension:
+
+record-extension
+    Record Language Extensions.
+
+    .. math::
+
+        \left\{ \begin{gathered}\mathop{\mathord{``}\mathtt{TraditionalRecordSyntax}\mathord{"}}\\\mathop{\mathord{``}\mathtt{DisambiguateRecordFields}\mathord{"}}\\\mathop{\mathord{``}\mathtt{DuplicateRecordFields}\mathord{"}}\\\mathop{\mathord{``}\mathtt{FieldSelectors}\mathord{"}}\\\mathop{\mathord{``}\mathtt{NamedFieldPuns}\mathord{"}}\\\mathop{\mathord{``}\mathtt{RecordWildCards}\mathord{"}}\\\mathop{\mathord{``}\mathtt{OverloadedRecordDot}\mathord{"}}\\\mathop{\mathord{``}\mathtt{OverloadedRecordUpdate}\mathord{"}}\end{gathered} \right\}
+
+.. _ghc-deriving-extension:
+
+deriving-extension
+    Language Extensions for deriving mechanisms.
+
+    .. math::
+
+        \left\{ \begin{gathered}\mathop{\mathord{``}\mathtt{EmptyDataDeriving}\mathord{"}}\\\mathop{\mathord{``}\mathtt{StandaloneDeriving}\mathord{"}}\\\mathop{\mathord{``}\mathtt{DeriveFoldable}\mathord{"}}\\\mathop{\mathord{``}\mathtt{DeriveFunctor}\mathord{"}}\\\mathop{\mathord{``}\mathtt{DeriveTraversable}\mathord{"}}\\\mathop{\mathord{``}\mathtt{DeriveDataTypeable}\mathord{"}}\\\mathop{\mathord{``}\mathtt{DeriveLift}\mathord{"}}\\\mathop{\mathord{``}\mathtt{GeneralizedNewtypeDeriving}\mathord{"}}\\\mathop{\mathord{``}\mathtt{GeneralisedNewtypeDeriving}\mathord{"}}\\\mathop{\mathord{``}\mathtt{DeriveAnyClass}\mathord{"}}\\\mathop{\mathord{``}\mathtt{DerivingStrategies}\mathord{"}}\\\mathop{\mathord{``}\mathtt{DerivingVia}\mathord{"}}\end{gathered} \right\}
+
+.. _ghc-pattern-extension:
+
+pattern-extension
+    Patterns Language Extensions.
+
+    .. math::
+
+        \left\{ \begin{gathered}\mathop{\mathord{``}\mathtt{PatternGuards}\mathord{"}}\\\mathop{\mathord{``}\mathtt{ViewPatterns}\mathord{"}}\\\mathop{\mathord{``}\mathtt{NPlusKPatterns}\mathord{"}}\\\mathop{\mathord{``}\mathtt{PatternSynonyms}\mathord{"}}\end{gathered} \right\}
+
+.. _ghc-classes-instances-extension:
+
+classes-instances-extension
+    Language Extensions for class and instance declarations.
+
+    .. math::
+
+        \left\{ \begin{gathered}\mathop{\mathord{``}\mathtt{MultiParamTypeClasses}\mathord{"}}\\\mathop{\mathord{``}\mathtt{UndecidableSuperClasses}\mathord{"}}\\\mathop{\mathord{``}\mathtt{ConstrainedClassMethods}\mathord{"}}\\\mathop{\mathord{``}\mathtt{DefaultSignatures}\mathord{"}}\\\mathop{\mathord{``}\mathtt{NullaryTypeClasses}\mathord{"}}\\\mathop{\mathord{``}\mathtt{FunctionalDependencies}\mathord{"}}\\\mathop{\mathord{``}\mathtt{TypeSynonymInstances}\mathord{"}}\\\mathop{\mathord{``}\mathtt{FlexibleInstances}\mathord{"}}\\\mathop{\mathord{``}\mathtt{UndecidableInstances}\mathord{"}}\\\mathop{\mathord{``}\mathtt{OverlappingInstances}\mathord{"}}\\\mathop{\mathord{``}\mathtt{IncoherentInstances}\mathord{"}}\\\mathop{\mathord{``}\mathtt{InstanceSigs}\mathord{"}}\end{gathered} \right\}
+
+.. _ghc-literal-extension:
+
+literal-extension
+    Literals Language Extensions.
+
+    .. math::
+
+        \left\{ \begin{gathered}\mathop{\mathord{``}\mathtt{NegativeLiterals}\mathord{"}}\\\mathop{\mathord{``}\mathtt{BinaryLiterals}\mathord{"}}\\\mathop{\mathord{``}\mathtt{HexFloatLiterals}\mathord{"}}\\\mathop{\mathord{``}\mathtt{NumDecimals}\mathord{"}}\\\mathop{\mathord{``}\mathtt{ExtendedLiterals}\mathord{"}}\\\mathop{\mathord{``}\mathtt{NumericUnderscores}\mathord{"}}\\\mathop{\mathord{``}\mathtt{OverloadedStrings}\mathord{"}}\\\mathop{\mathord{``}\mathtt{OverloadedLabels}\mathord{"}}\end{gathered} \right\}
+
+.. _ghc-constraint-extension:
+
+constraint-extension
+    Constraint Language Extensions.
+
+    .. math::
+
+        \left\{ \mathop{\mathord{``}\mathtt{FlexibleContexts}\mathord{"}}\mid\mathop{\mathord{``}\mathtt{ConstraintKinds}\mathord{"}}\mid\mathop{\mathord{``}\mathtt{QuantifiedConstraints}\mathord{"}} \right\}
+
+.. _ghc-type-signature-extension:
+
+type-signature-extension
+    Type Signature Language Extensions.
+
+    .. math::
+
+        \left\{ \begin{gathered}\mathop{\mathord{``}\mathtt{ExplicitForAll}\mathord{"}}\\\mathop{\mathord{``}\mathtt{AllowAmbiguousTypes}\mathord{"}}\\\mathop{\mathord{``}\mathtt{KindSignatures}\mathord{"}}\\\mathop{\mathord{``}\mathtt{ScopedTypeVariables}\mathord{"}}\\\mathop{\mathord{``}\mathtt{ImplicitParams}\mathord{"}}\\\mathop{\mathord{``}\mathtt{PartialTypeSignatures}\mathord{"}}\\\mathop{\mathord{``}\mathtt{NamedWildCards}\mathord{"}}\end{gathered} \right\}
+
+.. _ghc-binding-generalisation-extension:
+
+binding-generalisation-extension
+    Language Extensions for bindings and generalisation 
+
+    .. math::
+
+        \left\{ \mathop{\mathord{``}\mathtt{MonomorphismRestriction}\mathord{"}}\mid\mathop{\mathord{``}\mathtt{MonoLocalBinds}\mathord{"}} \right\}
+
+.. _ghc-template-haskell-extension:
+
+template-haskell-extension
+    Template Haskell Language Extensions.
+
+    .. math::
+
+        \left\{ \mathop{\mathord{``}\mathtt{TemplateHaskell}\mathord{"}}\mid\mathop{\mathord{``}\mathtt{TemplateHaskellQuotes}\mathord{"}}\mid\mathop{\mathord{``}\mathtt{QuasiQuotes}\mathord{"}} \right\}
+
+.. _ghc-bang-strict-extension:
+
+bang-strict-extension
+    Bang pattern and Strict Haskell Language Extensions.
+
+    .. math::
+
+        \left\{ \mathop{\mathord{``}\mathtt{BangPatterns}\mathord{"}}\mid\mathop{\mathord{``}\mathtt{StrictData}\mathord{"}}\mid\mathop{\mathord{``}\mathtt{Strict}\mathord{"}} \right\}
+
+.. _ghc-parallel-concurrent-extension:
+
+parallel-concurrent-extension
+    Parallel and Concurrent Language Extensions.
+
+    .. math::
+
+        \mathop{\mathord{``}\mathtt{StaticPointers}\mathord{"}}
+
+.. _ghc-unboxed-primitive-extension:
+
+unboxed-primitive-extension
+    Unboxed types and Primitive operations Language Extensions.
+
+    .. math::
+
+        \left\{ \begin{gathered}\mathop{\mathord{``}\mathtt{UnboxedTuples}\mathord{"}}\\\mathop{\mathord{``}\mathtt{UnboxedSums}\mathord{"}}\\\mathop{\mathord{``}\mathtt{UnliftedNewtypes}\mathord{"}}\\\mathop{\mathord{``}\mathtt{UnliftedDatatypes}\mathord{"}}\end{gathered} \right\}
+
+.. _ghc-foreign-extension:
+
+foreign-extension
+    Foreign function interface (FFI) Language Extensions.
+
+    .. math::
+
+        \left\{ \begin{gathered}\mathop{\mathord{``}\mathtt{ForeignFunctionInterface}\mathord{"}}\\\mathop{\mathord{``}\mathtt{UnliftedFFITypes}\mathord{"}}\\\mathop{\mathord{``}\mathtt{GHCForeignImportPrim}\mathord{"}}\\\mathop{\mathord{``}\mathtt{InterruptibleFFI}\mathord{"}}\\\mathop{\mathord{``}\mathtt{CApiFFI}\mathord{"}}\end{gathered} \right\}
+
+.. _ghc-safe-extension:
+
+safe-extension
+    Safe Haskell Language Extensions.
+
+    .. math::
+
+        \left\{ \mathop{\mathord{``}\mathtt{Safe}\mathord{"}}\mid\mathop{\mathord{``}\mathtt{Trustworthy}\mathord{"}}\mid\mathop{\mathord{``}\mathtt{Unsafe}\mathord{"}} \right\}
+
+.. _ghc-miscellaneous-extension:
+
+miscellaneous-extension
+    Miscellaneous Language Extensions.
+
+    .. math::
+
+        \mathop{\mathord{``}\mathtt{DeriveGeneric}\mathord{"}}
+
+.. _ghc-bugs-extension:
+
+bugs-extension
+    Language Extensions related to GHC bugs and infelicities.
+
+    .. math::
+
+        \mathop{\mathord{``}\mathtt{NondecreasingIndentation}\mathord{"}}
+
+.. _ghc-ungrouped-extension:
+
+ungrouped-extension
+    Language Extensions not belonging to other extension groups, includes undocumented extensions.
+
+    .. math::
+
+        \left\{ \begin{gathered}\mathop{\mathord{``}\mathtt{DoRec}\mathord{"}}\\\mathop{\mathord{``}\mathtt{PolymorphicComponents}\mathord{"}}\\\mathop{\mathord{``}\mathtt{PatternSignatures}\mathord{"}}\\\mathop{\mathord{``}\mathtt{Generics}\mathord{"}}\\\mathop{\mathord{``}\mathtt{ExtensibleRecords}\mathord{"}}\\\mathop{\mathord{``}\mathtt{RestrictedTypeSynonyms}\mathord{"}}\\\mathop{\mathord{``}\mathtt{HereDocuments}\mathord{"}}\\\mathop{\mathord{``}\mathtt{RecordPuns}\mathord{"}}\\\mathop{\mathord{``}\mathtt{MonoPatBinds}\mathord{"}}\\\mathop{\mathord{``}\mathtt{RelaxedPolyRec}\mathord{"}}\\\mathop{\mathord{``}\mathtt{NewQualifiedOperators}\mathord{"}}\\\mathop{\mathord{``}\mathtt{XmlSyntax}\mathord{"}}\\\mathop{\mathord{``}\mathtt{RegularPatterns}\mathord{"}}\\\mathop{\mathord{``}\mathtt{DoAndIfThenElse}\mathord{"}}\\\mathop{\mathord{``}\mathtt{SafeImports}\mathord{"}}\\\mathop{\mathord{``}\mathtt{ParallelArrays}\mathord{"}}\\\mathop{\mathord{``}\mathtt{AutoDeriveTypeable}\mathord{"}}\\\mathop{\mathord{``}\mathtt{JavaScriptFFI}\mathord{"}}\\\mathop{\mathord{``}\mathtt{MonadFailDesugaring}\mathord{"}}\\\mathop{\mathord{``}\mathtt{AlternativeLayoutRule}\mathord{"}}\\\mathop{\mathord{``}\mathtt{AlternativeLayoutRuleTransitional}\mathord{"}}\\\mathop{\mathord{``}\mathtt{RelaxedLayout}\mathord{"}}\end{gathered} \right\}
+
+
+GHC build info fields
+---------------------
+
+These are cabal package build info fields that are more related to GHC, the
+Haskell compiler, than they are to Cabal.
+
+.. _ghc-default-extensions:
+
+default-extensions
+    * Monoidal field
+    * Available since ``cabal-version: 1.10``.
+    * Documentation of :pkg-field:`library:default-extensions`
+
+    .. math::
+
+        \mathrm{optcommalist}\left\{ \mathop{\mathit{enable\text{-}extension}}\mid\mathop{\mathit{disable\text{-}extension}} \right\}
+
+.. _ghc-default-language:
+
+default-language
+    * Optional field
+    * Available since ``cabal-version: 1.10``.
+    * Documentation of :pkg-field:`library:default-language`
+
+    .. math::
+
+        \left\{ \mathop{\mathord{``}\mathtt{GHC2021}\mathord{"}}\mid\mathop{\mathord{``}\mathtt{Haskell2010}\mathord{"}}\mid\mathop{\mathord{``}\mathtt{Haskell98}\mathord{"}} \right\}
+
+.. _ghc-extensions:
+
+extensions
+    * Monoidal field
+    * Deprecated since ``cabal-version: 1.12``: Please use 'default-extensions' or 'other-extensions' fields.
+    * Removed in ``cabal-version: 3.0``: Please use 'default-extensions' or 'other-extensions' fields.
+
+    .. math::
+
+        \mathrm{optcommalist}\left\{ \mathop{\mathit{enable\text{-}extension}}\mid\mathop{\mathit{disable\text{-}extension}} \right\}
+
+.. _ghc-other-extensions:
+
+other-extensions
+    * Monoidal field
+    * Documentation of :pkg-field:`library:other-extensions`
+
+    .. math::
+
+        \mathrm{optcommalist}\left\{ \mathop{\mathit{enable\text{-}extension}}\mid\mathop{\mathit{disable\text{-}extension}} \right\}
+
+.. _ghc-other-languages:
+
+other-languages
+    * Monoidal field
+    * Available since ``cabal-version: 1.10``.
+    * Documentation of :pkg-field:`library:other-languages`
+
+    .. math::
+
+        \mathrm{optcommalist}\left\{ \mathop{\mathord{``}\mathtt{GHC2021}\mathord{"}}\mid\mathop{\mathord{``}\mathtt{Haskell2010}\mathord{"}}\mid\mathop{\mathord{``}\mathtt{Haskell98}\mathord{"}} \right\}
+
+
+
diff --git a/doc/index.rst b/doc/index.rst
index 69109a67685..210d2e07f0f 100644
--- a/doc/index.rst
+++ b/doc/index.rst
@@ -29,7 +29,6 @@ Welcome to the Cabal User Guide
    external-commands
    setup-commands
    file-format-changelog
-   buildinfo-fields-reference
 
 .. toctree::
    :caption: Cabal Explanation
@@ -39,3 +38,11 @@ Welcome to the Cabal User Guide
    cabal-context
    package-concepts
    cabal-interface-stability
+
+.. toctree::
+   :caption: Syntax Reference
+   :numbered:
+   :maxdepth: 2
+
+   cabal-package-syntax
+   ghc-syntax