diff --git a/Builds/levelization/results/loops.txt b/Builds/levelization/results/loops.txt
index ca01e0f5e82..7c132f5429e 100644
--- a/Builds/levelization/results/loops.txt
+++ b/Builds/levelization/results/loops.txt
@@ -4,9 +4,6 @@ Loop: test.jtx test.toplevel
 Loop: test.jtx test.unit_test
   test.unit_test == test.jtx
 
-Loop: xrpl.basics xrpl.json
-  xrpl.json ~= xrpl.basics
-
 Loop: xrpld.app xrpld.core
   xrpld.app > xrpld.core
 
diff --git a/Builds/levelization/results/ordering.txt b/Builds/levelization/results/ordering.txt
index 396c99cb711..b2745b906c3 100644
--- a/Builds/levelization/results/ordering.txt
+++ b/Builds/levelization/results/ordering.txt
@@ -1,5 +1,4 @@
 libxrpl.basics > xrpl.basics
-libxrpl.basics > xrpl.protocol
 libxrpl.crypto > xrpl.basics
 libxrpl.json > xrpl.basics
 libxrpl.json > xrpl.json
@@ -130,6 +129,7 @@ test.shamap > xrpl.protocol
 test.toplevel > test.csf
 test.toplevel > xrpl.json
 test.unit_test > xrpl.basics
+xrpl.json > xrpl.basics
 xrpl.protocol > xrpl.basics
 xrpl.protocol > xrpl.json
 xrpl.resource > xrpl.basics
diff --git a/cmake/RippledCore.cmake b/cmake/RippledCore.cmake
index 3b850354ed4..aac7db77875 100644
--- a/cmake/RippledCore.cmake
+++ b/cmake/RippledCore.cmake
@@ -47,6 +47,57 @@ target_link_libraries(xrpl.libpb
     gRPC::grpc++
 )
 
+# TODO: Clean up the number of library targets later.
+add_library(xrpl.imports.main INTERFACE)
+target_link_libraries(xrpl.imports.main INTERFACE
+    LibArchive::LibArchive
+    OpenSSL::Crypto
+    Ripple::boost
+    Ripple::opts
+    Ripple::syslibs
+    absl::random_random
+    date::date
+    ed25519::ed25519
+    secp256k1::secp256k1
+    xxHash::xxhash
+)
+
+include(add_module)
+include(target_link_modules)
+
+# Level 01
+add_module(xrpl beast)
+target_link_libraries(xrpl.libxrpl.beast PUBLIC
+  xrpl.imports.main
+  xrpl.libpb
+)
+
+# Level 02
+add_module(xrpl basics)
+target_link_libraries(xrpl.libxrpl.basics PUBLIC xrpl.libxrpl.beast)
+
+# Level 03
+add_module(xrpl json)
+target_link_libraries(xrpl.libxrpl.json PUBLIC xrpl.libxrpl.basics)
+
+add_module(xrpl crypto)
+target_link_libraries(xrpl.libxrpl.crypto PUBLIC xrpl.libxrpl.basics)
+
+# Level 04
+add_module(xrpl protocol)
+target_link_libraries(xrpl.libxrpl.protocol PUBLIC
+  xrpl.libxrpl.crypto
+  xrpl.libxrpl.json
+)
+
+# Level 05
+add_module(xrpl resource)
+target_link_libraries(xrpl.libxrpl.resource PUBLIC xrpl.libxrpl.protocol)
+
+add_module(xrpl server)
+target_link_libraries(xrpl.libxrpl.server PUBLIC xrpl.libxrpl.protocol)
+
+
 add_library(xrpl.libxrpl)
 set_target_properties(xrpl.libxrpl PROPERTIES OUTPUT_NAME xrpl)
 if(unity)
@@ -60,7 +111,19 @@ file(GLOB_RECURSE sources CONFIGURE_DEPENDS
 )
 target_sources(xrpl.libxrpl PRIVATE ${sources})
 
+target_link_modules(xrpl PUBLIC
+  basics
+  beast
+  crypto
+  json
+  protocol
+  resource
+  server
+)
+
 target_include_directories(xrpl.libxrpl
+  PRIVATE
+    $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/src>
   PUBLIC
     $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include>
     $<INSTALL_INTERFACE:include>)
diff --git a/cmake/RippledInstall.cmake b/cmake/RippledInstall.cmake
index 3199c9a19b8..3a41aab8368 100644
--- a/cmake/RippledInstall.cmake
+++ b/cmake/RippledInstall.cmake
@@ -8,7 +8,15 @@ install (
     opts
     ripple_syslibs
     ripple_boost
+    xrpl.imports.main
     xrpl.libpb
+    xrpl.libxrpl.basics
+    xrpl.libxrpl.beast
+    xrpl.libxrpl.crypto
+    xrpl.libxrpl.json
+    xrpl.libxrpl.protocol
+    xrpl.libxrpl.resource
+    xrpl.libxrpl.server
     xrpl.libxrpl
   EXPORT RippleExports
   LIBRARY DESTINATION lib
diff --git a/cmake/add_module.cmake b/cmake/add_module.cmake
new file mode 100644
index 00000000000..bcfce1bf600
--- /dev/null
+++ b/cmake/add_module.cmake
@@ -0,0 +1,37 @@
+include(isolate_headers)
+
+# Create an OBJECT library target named
+#
+#   ${PROJECT_NAME}.lib${parent}.${name}
+#
+# with sources in src/lib${parent}/${name}
+# and headers in include/${parent}/${name}
+# that cannot include headers from other directories in include/
+# unless they come through linked libraries.
+#
+# add_module(parent a)
+# add_module(parent b)
+# target_link_libraries(project.libparent.b PUBLIC project.libparent.a)
+function(add_module parent name)
+  set(target ${PROJECT_NAME}.lib${parent}.${name})
+  add_library(${target} OBJECT)
+  file(GLOB_RECURSE sources CONFIGURE_DEPENDS
+    "${CMAKE_CURRENT_SOURCE_DIR}/src/lib${parent}/${name}/*.cpp"
+  )
+  target_sources(${target} PRIVATE ${sources})
+  target_include_directories(${target} PUBLIC
+    "$<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}>"
+  )
+  isolate_headers(
+    ${target}
+    "${CMAKE_CURRENT_SOURCE_DIR}/include"
+    "${CMAKE_CURRENT_SOURCE_DIR}/include/${parent}/${name}"
+    PUBLIC
+  )
+  isolate_headers(
+    ${target}
+    "${CMAKE_CURRENT_SOURCE_DIR}/src"
+    "${CMAKE_CURRENT_SOURCE_DIR}/src/lib${parent}/${name}"
+    PRIVATE
+  )
+endfunction()
diff --git a/cmake/isolate_headers.cmake b/cmake/isolate_headers.cmake
new file mode 100644
index 00000000000..dfc73366594
--- /dev/null
+++ b/cmake/isolate_headers.cmake
@@ -0,0 +1,46 @@
+# Consider include directory B nested under prefix A:
+#
+#     /path/to/A/then/to/B/...
+#
+# Call C the relative path from A to B.
+# C is what we want to write in `#include` directives:
+#
+#     #include <then/to/B/...>
+#
+# Examples, all from the `jobqueue` module:
+#
+#   - Library public headers:
+#     B = /include/xrpl/jobqueue
+#     A = /include/
+#     C = xrpl/jobqueue
+#
+#   - Library private headers:
+#     B = /src/libxrpl/jobqueue
+#     A = /src/
+#     C = libxrpl/jobqueue
+#
+#   - Test private headers:
+#     B = /tests/jobqueue
+#     A = /
+#     C = tests/jobqueue
+#
+# To isolate headers from each other,
+# we want to create a symlink Y that points to B,
+# within a subdirectory X of the `CMAKE_BINARY_DIR`,
+# that has the same relative path C between X and Y,
+# and then add X as an include directory of the target,
+# sometimes `PUBLIC` and sometimes `PRIVATE`.
+# The Cs are all guaranteed to be unique.
+# We can guarantee a unique X per target by using
+# `${CMAKE_CURRENT_BINARY_DIR}/include/${target}`.
+#
+# isolate_headers(target A B scope)
+function(isolate_headers target A B scope)
+  file(RELATIVE_PATH C "${A}" "${B}")
+  set(X "${CMAKE_CURRENT_BINARY_DIR}/modules/${target}")
+  set(Y "${X}/${C}")
+  cmake_path(GET Y PARENT_PATH parent)
+  file(MAKE_DIRECTORY "${parent}")
+  file(CREATE_LINK "${B}" "${Y}" SYMBOLIC)
+  target_include_directories(${target} ${scope} "$<BUILD_INTERFACE:${X}>")
+endfunction()
diff --git a/cmake/target_link_modules.cmake b/cmake/target_link_modules.cmake
new file mode 100644
index 00000000000..acbf67903a1
--- /dev/null
+++ b/cmake/target_link_modules.cmake
@@ -0,0 +1,24 @@
+# Link a library to its modules (see: `add_module`)
+# and remove the module sources from the library's sources.
+#
+# add_module(parent a)
+# add_module(parent b)
+# target_link_libraries(project.libparent.b PUBLIC project.libparent.a)
+# add_library(project.libparent)
+# target_link_modules(parent PUBLIC a b)
+function(target_link_modules parent scope)
+  set(library ${PROJECT_NAME}.lib${parent})
+  foreach(name ${ARGN})
+    set(module ${library}.${name})
+    get_target_property(sources ${library} SOURCES)
+    list(LENGTH sources before)
+    get_target_property(dupes ${module} SOURCES)
+    list(LENGTH dupes expected)
+    list(REMOVE_ITEM sources ${dupes})
+    list(LENGTH sources after)
+    math(EXPR actual "${before} - ${after}")
+    message(STATUS "${module} with ${expected} sources took ${actual} sources from ${library}")
+    set_target_properties(${library} PROPERTIES SOURCES "${sources}")
+    target_link_libraries(${library} ${scope} ${module})
+  endforeach()
+endfunction()
diff --git a/include/xrpl/basics/Number.h b/include/xrpl/basics/Number.h
index 30ce3f73173..de20dc490ae 100644
--- a/include/xrpl/basics/Number.h
+++ b/include/xrpl/basics/Number.h
@@ -20,7 +20,6 @@
 #ifndef RIPPLE_BASICS_NUMBER_H_INCLUDED
 #define RIPPLE_BASICS_NUMBER_H_INCLUDED
 
-#include <xrpl/basics/XRPAmount.h>
 #include <cstdint>
 #include <limits>
 #include <ostream>
@@ -51,8 +50,6 @@ class Number
     explicit Number(rep mantissa, int exponent);
     explicit constexpr Number(rep mantissa, int exponent, unchecked) noexcept;
 
-    Number(XRPAmount const& x);
-
     constexpr rep
     mantissa() const noexcept;
     constexpr int
@@ -88,8 +85,7 @@ class Number
     static constexpr Number
     lowest() noexcept;
 
-    explicit operator XRPAmount() const;  // round to nearest, even on tie
-    explicit operator rep() const;        // round to nearest, even on tie
+    explicit operator rep() const;  // round to nearest, even on tie
 
     friend constexpr bool
     operator==(Number const& x, Number const& y) noexcept
@@ -206,10 +202,6 @@ inline Number::Number(rep mantissa) : Number{mantissa, 0}
 {
 }
 
-inline Number::Number(XRPAmount const& x) : Number{x.drops()}
-{
-}
-
 inline constexpr Number::rep
 Number::mantissa() const noexcept
 {
diff --git a/include/xrpl/basics/SHAMapHash.h b/include/xrpl/basics/SHAMapHash.h
index 7e93ead78d3..2d2dcdc3efa 100644
--- a/include/xrpl/basics/SHAMapHash.h
+++ b/include/xrpl/basics/SHAMapHash.h
@@ -21,6 +21,7 @@
 #define RIPPLE_BASICS_SHAMAP_HASH_H_INCLUDED
 
 #include <xrpl/basics/base_uint.h>
+#include <xrpl/basics/partitioned_unordered_map.h>
 
 #include <ostream>
 
@@ -108,6 +109,13 @@ operator!=(SHAMapHash const& x, SHAMapHash const& y)
     return !(x == y);
 }
 
+template <>
+inline std::size_t
+extract(SHAMapHash const& key)
+{
+    return *reinterpret_cast<std::size_t const*>(key.as_uint256().data());
+}
+
 }  // namespace ripple
 
 #endif  // RIPPLE_BASICS_SHAMAP_HASH_H_INCLUDED
diff --git a/include/xrpl/basics/base_uint.h b/include/xrpl/basics/base_uint.h
index 2b44d3072ee..9c58c959d02 100644
--- a/include/xrpl/basics/base_uint.h
+++ b/include/xrpl/basics/base_uint.h
@@ -29,6 +29,7 @@
 #include <xrpl/basics/Slice.h>
 #include <xrpl/basics/contract.h>
 #include <xrpl/basics/hardened_hash.h>
+#include <xrpl/basics/partitioned_unordered_map.h>
 #include <xrpl/basics/strHex.h>
 #include <xrpl/beast/utility/Zero.h>
 #include <boost/endian/conversion.hpp>
@@ -630,6 +631,17 @@ operator<<(std::ostream& out, base_uint<Bits, Tag> const& u)
     return out << to_string(u);
 }
 
+template <>
+inline std::size_t
+extract(uint256 const& key)
+{
+    std::size_t result;
+    // Use memcpy to avoid unaligned UB
+    // (will optimize to equivalent code)
+    std::memcpy(&result, key.data(), sizeof(std::size_t));
+    return result;
+}
+
 #ifndef __INTELLISENSE__
 static_assert(sizeof(uint128) == 128 / 8, "There should be no padding bytes");
 static_assert(sizeof(uint160) == 160 / 8, "There should be no padding bytes");
diff --git a/include/xrpl/basics/partitioned_unordered_map.h b/include/xrpl/basics/partitioned_unordered_map.h
index 08f4cba9d3e..6e8ada156fe 100644
--- a/include/xrpl/basics/partitioned_unordered_map.h
+++ b/include/xrpl/basics/partitioned_unordered_map.h
@@ -20,9 +20,12 @@
 #ifndef RIPPLE_BASICS_PARTITIONED_UNORDERED_MAP_H
 #define RIPPLE_BASICS_PARTITIONED_UNORDERED_MAP_H
 
+#include <xrpl/beast/hash/uhash.h>
+
 #include <cassert>
 #include <functional>
 #include <optional>
+#include <string>
 #include <thread>
 #include <unordered_map>
 #include <utility>
@@ -31,8 +34,18 @@
 namespace ripple {
 
 template <typename Key>
-std::size_t
-partitioner(Key const& key, std::size_t const numPartitions);
+static std::size_t
+extract(Key const& key)
+{
+    return key;
+}
+
+template <>
+inline std::size_t
+extract(std::string const& key)
+{
+    return ::beast::uhash<>{}(key);
+}
 
 template <
     typename Key,
@@ -211,7 +224,7 @@ class partitioned_unordered_map
     std::size_t
     partitioner(Key const& key) const
     {
-        return ripple::partitioner(key, partitions_);
+        return extract(key) % partitions_;
     }
 
     template <class T>
diff --git a/include/xrpl/protocol/AmountConversions.h b/include/xrpl/protocol/AmountConversions.h
index 0348e3c975d..c09218aa2eb 100644
--- a/include/xrpl/protocol/AmountConversions.h
+++ b/include/xrpl/protocol/AmountConversions.h
@@ -21,8 +21,8 @@
 #define RIPPLE_PROTOCOL_AMOUNTCONVERSION_H_INCLUDED
 
 #include <xrpl/basics/IOUAmount.h>
-#include <xrpl/basics/XRPAmount.h>
 #include <xrpl/protocol/STAmount.h>
+#include <xrpl/protocol/XRPAmount.h>
 
 #include <type_traits>
 
diff --git a/include/xrpl/basics/FeeUnits.h b/include/xrpl/protocol/FeeUnits.h
similarity index 98%
rename from include/xrpl/basics/FeeUnits.h
rename to include/xrpl/protocol/FeeUnits.h
index 9d5e6e216a4..265a58d4ae9 100644
--- a/include/xrpl/basics/FeeUnits.h
+++ b/include/xrpl/protocol/FeeUnits.h
@@ -19,22 +19,30 @@
 #ifndef BASICS_FEES_H_INCLUDED
 #define BASICS_FEES_H_INCLUDED
 
-#include <xrpl/basics/XRPAmount.h>
+#include <xrpl/basics/safe_cast.h>
+#include <xrpl/beast/utility/Zero.h>
+#include <xrpl/json/json_value.h>
+
 #include <boost/multiprecision/cpp_int.hpp>
-#include <limits>
-#include <utility>
+#include <boost/operators.hpp>
 
 #include <cassert>
 #include <cmath>
 #include <ios>
 #include <iosfwd>
+#include <limits>
+#include <optional>
 #include <sstream>
 #include <string>
+#include <utility>
 
 namespace ripple {
 
 namespace feeunit {
 
+/** "drops" are the smallest divisible amount of XRP. This is what most
+    of the code uses. */
+struct dropTag;
 /** "fee units" calculations are a not-really-unitless value that is used
     to express the cost of a given transaction vs. a reference transaction.
     They are primarily used by the Transactor classes. */
diff --git a/include/xrpl/protocol/Fees.h b/include/xrpl/protocol/Fees.h
index 7b4671a91d9..4393f1a1d9c 100644
--- a/include/xrpl/protocol/Fees.h
+++ b/include/xrpl/protocol/Fees.h
@@ -20,7 +20,7 @@
 #ifndef RIPPLE_PROTOCOL_FEES_H_INCLUDED
 #define RIPPLE_PROTOCOL_FEES_H_INCLUDED
 
-#include <xrpl/basics/XRPAmount.h>
+#include <xrpl/protocol/XRPAmount.h>
 
 namespace ripple {
 
diff --git a/include/xrpl/protocol/LedgerHeader.h b/include/xrpl/protocol/LedgerHeader.h
index 663eb709be2..0b35979971a 100644
--- a/include/xrpl/protocol/LedgerHeader.h
+++ b/include/xrpl/protocol/LedgerHeader.h
@@ -21,11 +21,11 @@
 #define RIPPLE_PROTOCOL_LEDGERHEADER_H_INCLUDED
 
 #include <xrpl/basics/Slice.h>
-#include <xrpl/basics/XRPAmount.h>
 #include <xrpl/basics/base_uint.h>
 #include <xrpl/basics/chrono.h>
 #include <xrpl/protocol/Protocol.h>
 #include <xrpl/protocol/Serializer.h>
+#include <xrpl/protocol/XRPAmount.h>
 
 namespace ripple {
 
diff --git a/include/xrpl/protocol/PayChan.h b/include/xrpl/protocol/PayChan.h
index 8344120ccd6..b552b591af2 100644
--- a/include/xrpl/protocol/PayChan.h
+++ b/include/xrpl/protocol/PayChan.h
@@ -20,10 +20,10 @@
 #ifndef RIPPLE_PROTOCOL_PAYCHAN_H_INCLUDED
 #define RIPPLE_PROTOCOL_PAYCHAN_H_INCLUDED
 
-#include <xrpl/basics/XRPAmount.h>
 #include <xrpl/basics/base_uint.h>
 #include <xrpl/protocol/HashPrefix.h>
 #include <xrpl/protocol/Serializer.h>
+#include <xrpl/protocol/XRPAmount.h>
 
 namespace ripple {
 
diff --git a/include/xrpl/protocol/Protocol.h b/include/xrpl/protocol/Protocol.h
index 8d8a71dfef8..5aa14d2931b 100644
--- a/include/xrpl/protocol/Protocol.h
+++ b/include/xrpl/protocol/Protocol.h
@@ -22,6 +22,7 @@
 
 #include <xrpl/basics/ByteUtilities.h>
 #include <xrpl/basics/base_uint.h>
+#include <xrpl/basics/partitioned_unordered_map.h>
 #include <cstdint>
 
 namespace ripple {
diff --git a/include/xrpl/protocol/Quality.h b/include/xrpl/protocol/Quality.h
index 1ee2cc9f686..12cdb77845e 100644
--- a/include/xrpl/protocol/Quality.h
+++ b/include/xrpl/protocol/Quality.h
@@ -21,9 +21,9 @@
 #define RIPPLE_PROTOCOL_QUALITY_H_INCLUDED
 
 #include <xrpl/basics/IOUAmount.h>
-#include <xrpl/basics/XRPAmount.h>
 #include <xrpl/protocol/AmountConversions.h>
 #include <xrpl/protocol/STAmount.h>
+#include <xrpl/protocol/XRPAmount.h>
 
 #include <algorithm>
 #include <cstdint>
diff --git a/include/xrpl/protocol/STAmount.h b/include/xrpl/protocol/STAmount.h
index 3eed0860f54..84e57ac40a2 100644
--- a/include/xrpl/protocol/STAmount.h
+++ b/include/xrpl/protocol/STAmount.h
@@ -24,11 +24,11 @@
 #include <xrpl/basics/IOUAmount.h>
 #include <xrpl/basics/LocalValue.h>
 #include <xrpl/basics/Number.h>
-#include <xrpl/basics/XRPAmount.h>
 #include <xrpl/protocol/Issue.h>
 #include <xrpl/protocol/SField.h>
 #include <xrpl/protocol/STBase.h>
 #include <xrpl/protocol/Serializer.h>
+#include <xrpl/protocol/XRPAmount.h>
 #include <xrpl/protocol/json_get_or_throw.h>
 
 namespace ripple {
diff --git a/include/xrpl/protocol/STObject.h b/include/xrpl/protocol/STObject.h
index b3cef83de5f..5e26ff2f465 100644
--- a/include/xrpl/protocol/STObject.h
+++ b/include/xrpl/protocol/STObject.h
@@ -21,10 +21,10 @@
 #define RIPPLE_PROTOCOL_STOBJECT_H_INCLUDED
 
 #include <xrpl/basics/CountedObject.h>
-#include <xrpl/basics/FeeUnits.h>
 #include <xrpl/basics/Slice.h>
 #include <xrpl/basics/chrono.h>
 #include <xrpl/basics/contract.h>
+#include <xrpl/protocol/FeeUnits.h>
 #include <xrpl/protocol/HashPrefix.h>
 #include <xrpl/protocol/SOTemplate.h>
 #include <xrpl/protocol/STAmount.h>
diff --git a/include/xrpl/protocol/STValidation.h b/include/xrpl/protocol/STValidation.h
index 6cae0971f51..4183021fc32 100644
--- a/include/xrpl/protocol/STValidation.h
+++ b/include/xrpl/protocol/STValidation.h
@@ -20,8 +20,8 @@
 #ifndef RIPPLE_PROTOCOL_STVALIDATION_H_INCLUDED
 #define RIPPLE_PROTOCOL_STVALIDATION_H_INCLUDED
 
-#include <xrpl/basics/FeeUnits.h>
 #include <xrpl/basics/Log.h>
+#include <xrpl/protocol/FeeUnits.h>
 #include <xrpl/protocol/PublicKey.h>
 #include <xrpl/protocol/STObject.h>
 #include <xrpl/protocol/SecretKey.h>
diff --git a/include/xrpl/protocol/SystemParameters.h b/include/xrpl/protocol/SystemParameters.h
index 7531a0d5fb9..af492340545 100644
--- a/include/xrpl/protocol/SystemParameters.h
+++ b/include/xrpl/protocol/SystemParameters.h
@@ -20,8 +20,8 @@
 #ifndef RIPPLE_PROTOCOL_SYSTEMPARAMETERS_H_INCLUDED
 #define RIPPLE_PROTOCOL_SYSTEMPARAMETERS_H_INCLUDED
 
-#include <xrpl/basics/XRPAmount.h>
 #include <xrpl/basics/chrono.h>
+#include <xrpl/protocol/XRPAmount.h>
 #include <cstdint>
 #include <string>
 
diff --git a/include/xrpl/basics/XRPAmount.h b/include/xrpl/protocol/XRPAmount.h
similarity index 96%
rename from include/xrpl/basics/XRPAmount.h
rename to include/xrpl/protocol/XRPAmount.h
index 1d3b32f169b..6f8c7854087 100644
--- a/include/xrpl/basics/XRPAmount.h
+++ b/include/xrpl/protocol/XRPAmount.h
@@ -20,10 +20,11 @@
 #ifndef RIPPLE_BASICS_XRPAMOUNT_H_INCLUDED
 #define RIPPLE_BASICS_XRPAMOUNT_H_INCLUDED
 
+#include <xrpl/basics/Number.h>
 #include <xrpl/basics/contract.h>
-#include <xrpl/basics/safe_cast.h>
 #include <xrpl/beast/utility/Zero.h>
 #include <xrpl/json/json_value.h>
+#include <xrpl/protocol/FeeUnits.h>
 
 #include <boost/multiprecision/cpp_int.hpp>
 #include <boost/operators.hpp>
@@ -35,14 +36,6 @@
 
 namespace ripple {
 
-namespace feeunit {
-
-/** "drops" are the smallest divisible amount of XRP. This is what most
-    of the code uses. */
-struct dropTag;
-
-}  // namespace feeunit
-
 class XRPAmount : private boost::totally_ordered<XRPAmount>,
                   private boost::additive<XRPAmount>,
                   private boost::equality_comparable<XRPAmount, std::int64_t>,
@@ -61,6 +54,11 @@ class XRPAmount : private boost::totally_ordered<XRPAmount>,
     constexpr XRPAmount&
     operator=(XRPAmount const& other) = default;
 
+    explicit XRPAmount(Number const& x)
+        : XRPAmount(static_cast<decltype(drops_)>(x))
+    {
+    }
+
     constexpr XRPAmount(beast::Zero) : drops_(0)
     {
     }
@@ -160,6 +158,11 @@ class XRPAmount : private boost::totally_ordered<XRPAmount>,
         return drops_ != 0;
     }
 
+    operator Number() const noexcept
+    {
+        return drops();
+    }
+
     /** Return the sign of the amount */
     constexpr int
     signum() const noexcept
diff --git a/src/libxrpl/basics/Number.cpp b/src/libxrpl/basics/Number.cpp
index 14260b653a2..e24f224bf45 100644
--- a/src/libxrpl/basics/Number.cpp
+++ b/src/libxrpl/basics/Number.cpp
@@ -499,11 +499,6 @@ Number::operator rep() const
     return drops;
 }
 
-Number::operator XRPAmount() const
-{
-    return XRPAmount{static_cast<rep>(*this)};
-}
-
 std::string
 to_string(Number const& amount)
 {
diff --git a/src/libxrpl/basics/partitioned_unordered_map.cpp b/src/libxrpl/basics/partitioned_unordered_map.cpp
deleted file mode 100644
index a6d02cd2c6f..00000000000
--- a/src/libxrpl/basics/partitioned_unordered_map.cpp
+++ /dev/null
@@ -1,82 +0,0 @@
-//------------------------------------------------------------------------------
-/*
-    This file is part of rippled: https://github.com/ripple/rippled
-    Copyright (c) 2021 Ripple Labs Inc.
-
-    Permission to use, copy, modify, and/or distribute this software for any
-    purpose  with  or without fee is hereby granted, provided that the above
-    copyright notice and this permission notice appear in all copies.
-
-    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
-    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
-    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
-    ANY  SPECIAL ,  DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
-    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
-    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
-    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
-*/
-//==============================================================================
-
-#include <xrpl/basics/partitioned_unordered_map.h>
-
-#include <xrpl/basics/SHAMapHash.h>
-#include <xrpl/basics/base_uint.h>
-#include <xrpl/beast/hash/uhash.h>
-#include <xrpl/protocol/Protocol.h>
-#include <limits>
-#include <string>
-
-namespace ripple {
-
-static std::size_t
-extract(uint256 const& key)
-{
-    std::size_t result;
-    // Use memcpy to avoid unaligned UB
-    // (will optimize to equivalent code)
-    std::memcpy(&result, key.data(), sizeof(std::size_t));
-    return result;
-}
-
-static std::size_t
-extract(SHAMapHash const& key)
-{
-    return *reinterpret_cast<std::size_t const*>(key.as_uint256().data());
-}
-
-static std::size_t
-extract(LedgerIndex key)
-{
-    return static_cast<std::size_t>(key);
-}
-
-static std::size_t
-extract(std::string const& key)
-{
-    return ::beast::uhash<>{}(key);
-}
-
-template <typename Key>
-std::size_t
-partitioner(Key const& key, std::size_t const numPartitions)
-{
-    return extract(key) % numPartitions;
-}
-
-template std::size_t
-partitioner<LedgerIndex>(
-    LedgerIndex const& key,
-    std::size_t const numPartitions);
-
-template std::size_t
-partitioner<uint256>(uint256 const& key, std::size_t const numPartitions);
-
-template std::size_t
-partitioner<SHAMapHash>(SHAMapHash const& key, std::size_t const numPartitions);
-
-template std::size_t
-partitioner<std::string>(
-    std::string const& key,
-    std::size_t const numPartitions);
-
-}  // namespace ripple
diff --git a/src/test/basics/FeeUnits_test.cpp b/src/test/basics/FeeUnits_test.cpp
index 6608a072621..c32f98f1929 100644
--- a/src/test/basics/FeeUnits_test.cpp
+++ b/src/test/basics/FeeUnits_test.cpp
@@ -16,8 +16,8 @@
     OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */
 
-#include <xrpl/basics/FeeUnits.h>
 #include <xrpl/beast/unit_test.h>
+#include <xrpl/protocol/FeeUnits.h>
 #include <xrpl/protocol/SystemParameters.h>
 #include <type_traits>
 
diff --git a/src/test/basics/XRPAmount_test.cpp b/src/test/basics/XRPAmount_test.cpp
index c4c96dbfbde..f1032be365b 100644
--- a/src/test/basics/XRPAmount_test.cpp
+++ b/src/test/basics/XRPAmount_test.cpp
@@ -17,8 +17,8 @@
 */
 //==============================================================================
 
-#include <xrpl/basics/XRPAmount.h>
 #include <xrpl/beast/unit_test.h>
+#include <xrpl/protocol/XRPAmount.h>
 
 namespace ripple {
 
diff --git a/src/test/jtx/amount.h b/src/test/jtx/amount.h
index c8e0d0c3701..e797a40b402 100644
--- a/src/test/jtx/amount.h
+++ b/src/test/jtx/amount.h
@@ -23,8 +23,8 @@
 #include <test/jtx/Account.h>
 #include <test/jtx/amount.h>
 #include <test/jtx/tags.h>
-#include <xrpl/basics/FeeUnits.h>
 #include <xrpl/basics/contract.h>
+#include <xrpl/protocol/FeeUnits.h>
 #include <xrpl/protocol/Issue.h>
 #include <xrpl/protocol/STAmount.h>
 #include <cstdint>
diff --git a/src/xrpld/app/misc/LoadFeeTrack.h b/src/xrpld/app/misc/LoadFeeTrack.h
index 6c37864e2fd..875a7bb7dfa 100644
--- a/src/xrpld/app/misc/LoadFeeTrack.h
+++ b/src/xrpld/app/misc/LoadFeeTrack.h
@@ -20,10 +20,11 @@
 #ifndef RIPPLE_CORE_LOADFEETRACK_H_INCLUDED
 #define RIPPLE_CORE_LOADFEETRACK_H_INCLUDED
 
-#include <xrpl/basics/FeeUnits.h>
 #include <xrpl/basics/Log.h>
 #include <xrpl/beast/utility/Journal.h>
 #include <xrpl/json/json_value.h>
+#include <xrpl/protocol/FeeUnits.h>
+#include <xrpl/protocol/XRPAmount.h>
 #include <algorithm>
 #include <cstdint>
 #include <mutex>
diff --git a/src/xrpld/app/misc/detail/LoadFeeTrack.cpp b/src/xrpld/app/misc/detail/LoadFeeTrack.cpp
index 1267af594d0..50fb0ac14db 100644
--- a/src/xrpld/app/misc/detail/LoadFeeTrack.cpp
+++ b/src/xrpld/app/misc/detail/LoadFeeTrack.cpp
@@ -20,10 +20,10 @@
 #include <xrpld/app/misc/LoadFeeTrack.h>
 #include <xrpld/core/Config.h>
 #include <xrpld/ledger/ReadView.h>
-#include <xrpl/basics/FeeUnits.h>
 #include <xrpl/basics/Log.h>
 #include <xrpl/basics/contract.h>
 #include <xrpl/basics/safe_cast.h>
+#include <xrpl/protocol/FeeUnits.h>
 #include <xrpl/protocol/STAmount.h>
 #include <xrpl/protocol/jss.h>
 
diff --git a/src/xrpld/app/paths/Flow.cpp b/src/xrpld/app/paths/Flow.cpp
index c21d40c33b5..5707a6d4553 100644
--- a/src/xrpld/app/paths/Flow.cpp
+++ b/src/xrpld/app/paths/Flow.cpp
@@ -25,7 +25,7 @@
 #include <xrpld/app/paths/detail/StrandFlow.h>
 #include <xrpl/basics/IOUAmount.h>
 #include <xrpl/basics/Log.h>
-#include <xrpl/basics/XRPAmount.h>
+#include <xrpl/protocol/XRPAmount.h>
 
 #include <boost/container/flat_set.hpp>
 
diff --git a/src/xrpld/app/paths/detail/AmountSpec.h b/src/xrpld/app/paths/detail/AmountSpec.h
index 8a1117f9920..210880e4945 100644
--- a/src/xrpld/app/paths/detail/AmountSpec.h
+++ b/src/xrpld/app/paths/detail/AmountSpec.h
@@ -21,8 +21,8 @@
 #define RIPPLE_PATH_IMPL_AMOUNTSPEC_H_INCLUDED
 
 #include <xrpl/basics/IOUAmount.h>
-#include <xrpl/basics/XRPAmount.h>
 #include <xrpl/protocol/STAmount.h>
+#include <xrpl/protocol/XRPAmount.h>
 
 #include <optional>
 
diff --git a/src/xrpld/app/paths/detail/BookStep.cpp b/src/xrpld/app/paths/detail/BookStep.cpp
index 96971a516fc..d72da0f657a 100644
--- a/src/xrpld/app/paths/detail/BookStep.cpp
+++ b/src/xrpld/app/paths/detail/BookStep.cpp
@@ -26,11 +26,11 @@
 #include <xrpld/ledger/PaymentSandbox.h>
 #include <xrpl/basics/IOUAmount.h>
 #include <xrpl/basics/Log.h>
-#include <xrpl/basics/XRPAmount.h>
 #include <xrpl/basics/contract.h>
 #include <xrpl/protocol/Book.h>
 #include <xrpl/protocol/Feature.h>
 #include <xrpl/protocol/Quality.h>
+#include <xrpl/protocol/XRPAmount.h>
 
 #include <boost/container/flat_set.hpp>
 
diff --git a/src/xrpld/app/paths/detail/FlowDebugInfo.h b/src/xrpld/app/paths/detail/FlowDebugInfo.h
index 000db4e5714..81239de2f04 100644
--- a/src/xrpld/app/paths/detail/FlowDebugInfo.h
+++ b/src/xrpld/app/paths/detail/FlowDebugInfo.h
@@ -23,7 +23,7 @@
 #include <xrpld/app/paths/detail/AmountSpec.h>
 #include <xrpld/ledger/PaymentSandbox.h>
 #include <xrpl/basics/IOUAmount.h>
-#include <xrpl/basics/XRPAmount.h>
+#include <xrpl/protocol/XRPAmount.h>
 
 #include <boost/container/flat_map.hpp>
 
diff --git a/src/xrpld/app/paths/detail/PaySteps.cpp b/src/xrpld/app/paths/detail/PaySteps.cpp
index f28c1b96a7c..a2356b380b5 100644
--- a/src/xrpld/app/paths/detail/PaySteps.cpp
+++ b/src/xrpld/app/paths/detail/PaySteps.cpp
@@ -20,10 +20,10 @@
 #include <xrpld/app/paths/detail/Steps.h>
 #include <xrpld/ledger/ReadView.h>
 #include <xrpl/basics/IOUAmount.h>
-#include <xrpl/basics/XRPAmount.h>
 #include <xrpl/basics/contract.h>
 #include <xrpl/json/json_writer.h>
 #include <xrpl/protocol/Feature.h>
+#include <xrpl/protocol/XRPAmount.h>
 
 #include <algorithm>
 #include <numeric>
diff --git a/src/xrpld/app/paths/detail/StrandFlow.h b/src/xrpld/app/paths/detail/StrandFlow.h
index 329a4cc643f..c5365b2384d 100644
--- a/src/xrpld/app/paths/detail/StrandFlow.h
+++ b/src/xrpld/app/paths/detail/StrandFlow.h
@@ -30,8 +30,8 @@
 #include <xrpld/app/paths/detail/Steps.h>
 #include <xrpl/basics/IOUAmount.h>
 #include <xrpl/basics/Log.h>
-#include <xrpl/basics/XRPAmount.h>
 #include <xrpl/protocol/Feature.h>
+#include <xrpl/protocol/XRPAmount.h>
 
 #include <boost/container/flat_set.hpp>
 
diff --git a/src/xrpld/app/paths/detail/XRPEndpointStep.cpp b/src/xrpld/app/paths/detail/XRPEndpointStep.cpp
index ac88152c9dd..5ef9d99fddb 100644
--- a/src/xrpld/app/paths/detail/XRPEndpointStep.cpp
+++ b/src/xrpld/app/paths/detail/XRPEndpointStep.cpp
@@ -24,9 +24,9 @@
 #include <xrpld/ledger/PaymentSandbox.h>
 #include <xrpl/basics/IOUAmount.h>
 #include <xrpl/basics/Log.h>
-#include <xrpl/basics/XRPAmount.h>
 #include <xrpl/protocol/Feature.h>
 #include <xrpl/protocol/Quality.h>
+#include <xrpl/protocol/XRPAmount.h>
 
 #include <boost/container/flat_set.hpp>
 
diff --git a/src/xrpld/app/tx/detail/ApplyContext.h b/src/xrpld/app/tx/detail/ApplyContext.h
index 45de05a73db..6ffe7a4d576 100644
--- a/src/xrpld/app/tx/detail/ApplyContext.h
+++ b/src/xrpld/app/tx/detail/ApplyContext.h
@@ -23,9 +23,9 @@
 #include <xrpld/app/main/Application.h>
 #include <xrpld/core/Config.h>
 #include <xrpld/ledger/ApplyViewImpl.h>
-#include <xrpl/basics/XRPAmount.h>
 #include <xrpl/beast/utility/Journal.h>
 #include <xrpl/protocol/STTx.h>
+#include <xrpl/protocol/XRPAmount.h>
 #include <optional>
 #include <utility>
 
diff --git a/src/xrpld/app/tx/detail/DeleteAccount.cpp b/src/xrpld/app/tx/detail/DeleteAccount.cpp
index fb2f3fc507f..7cd629f56cd 100644
--- a/src/xrpld/app/tx/detail/DeleteAccount.cpp
+++ b/src/xrpld/app/tx/detail/DeleteAccount.cpp
@@ -24,10 +24,10 @@
 #include <xrpld/app/tx/detail/NFTokenUtils.h>
 #include <xrpld/app/tx/detail/SetSignerList.h>
 #include <xrpld/ledger/View.h>
-#include <xrpl/basics/FeeUnits.h>
 #include <xrpl/basics/Log.h>
 #include <xrpl/basics/mulDiv.h>
 #include <xrpl/protocol/Feature.h>
+#include <xrpl/protocol/FeeUnits.h>
 #include <xrpl/protocol/Indexes.h>
 #include <xrpl/protocol/Protocol.h>
 #include <xrpl/protocol/TxFlags.h>
diff --git a/src/xrpld/app/tx/detail/Escrow.cpp b/src/xrpld/app/tx/detail/Escrow.cpp
index e34b675998d..572b37b55ce 100644
--- a/src/xrpld/app/tx/detail/Escrow.cpp
+++ b/src/xrpld/app/tx/detail/Escrow.cpp
@@ -25,12 +25,12 @@
 #include <xrpld/ledger/ApplyView.h>
 #include <xrpld/ledger/View.h>
 #include <xrpl/basics/Log.h>
-#include <xrpl/basics/XRPAmount.h>
 #include <xrpl/basics/chrono.h>
 #include <xrpl/basics/safe_cast.h>
 #include <xrpl/protocol/Feature.h>
 #include <xrpl/protocol/Indexes.h>
 #include <xrpl/protocol/TxFlags.h>
+#include <xrpl/protocol/XRPAmount.h>
 #include <xrpl/protocol/digest.h>
 #include <xrpl/protocol/st.h>
 
diff --git a/src/xrpld/app/tx/detail/InvariantCheck.cpp b/src/xrpld/app/tx/detail/InvariantCheck.cpp
index f855ad8578c..22ad62d9a29 100644
--- a/src/xrpld/app/tx/detail/InvariantCheck.cpp
+++ b/src/xrpld/app/tx/detail/InvariantCheck.cpp
@@ -22,9 +22,9 @@
 #include <xrpld/app/tx/detail/NFTokenUtils.h>
 #include <xrpld/ledger/ReadView.h>
 #include <xrpld/ledger/View.h>
-#include <xrpl/basics/FeeUnits.h>
 #include <xrpl/basics/Log.h>
 #include <xrpl/protocol/Feature.h>
+#include <xrpl/protocol/FeeUnits.h>
 #include <xrpl/protocol/STArray.h>
 #include <xrpl/protocol/SystemParameters.h>
 #include <xrpl/protocol/TxFormats.h>
diff --git a/src/xrpld/app/tx/detail/PayChan.cpp b/src/xrpld/app/tx/detail/PayChan.cpp
index d17736c4738..94d489d8c22 100644
--- a/src/xrpld/app/tx/detail/PayChan.cpp
+++ b/src/xrpld/app/tx/detail/PayChan.cpp
@@ -21,13 +21,13 @@
 #include <xrpld/ledger/ApplyView.h>
 #include <xrpld/ledger/View.h>
 #include <xrpl/basics/Log.h>
-#include <xrpl/basics/XRPAmount.h>
 #include <xrpl/basics/chrono.h>
 #include <xrpl/protocol/Feature.h>
 #include <xrpl/protocol/Indexes.h>
 #include <xrpl/protocol/PayChan.h>
 #include <xrpl/protocol/PublicKey.h>
 #include <xrpl/protocol/TxFlags.h>
+#include <xrpl/protocol/XRPAmount.h>
 #include <xrpl/protocol/digest.h>
 #include <xrpl/protocol/st.h>
 
diff --git a/src/xrpld/app/tx/detail/Transactor.h b/src/xrpld/app/tx/detail/Transactor.h
index c587e5e1994..d7908749efd 100644
--- a/src/xrpld/app/tx/detail/Transactor.h
+++ b/src/xrpld/app/tx/detail/Transactor.h
@@ -22,8 +22,8 @@
 
 #include <xrpld/app/tx/applySteps.h>
 #include <xrpld/app/tx/detail/ApplyContext.h>
-#include <xrpl/basics/XRPAmount.h>
 #include <xrpl/beast/utility/Journal.h>
+#include <xrpl/protocol/XRPAmount.h>
 
 namespace ripple {
 
diff --git a/src/xrpld/app/tx/detail/XChainBridge.cpp b/src/xrpld/app/tx/detail/XChainBridge.cpp
index f5633903567..14a234bfa02 100644
--- a/src/xrpld/app/tx/detail/XChainBridge.cpp
+++ b/src/xrpld/app/tx/detail/XChainBridge.cpp
@@ -26,7 +26,6 @@
 #include <xrpld/ledger/View.h>
 #include <xrpl/basics/Log.h>
 #include <xrpl/basics/Number.h>
-#include <xrpl/basics/XRPAmount.h>
 #include <xrpl/basics/chrono.h>
 #include <xrpl/beast/utility/Journal.h>
 #include <xrpl/protocol/AccountID.h>
@@ -40,6 +39,7 @@
 #include <xrpl/protocol/TER.h>
 #include <xrpl/protocol/TxFlags.h>
 #include <xrpl/protocol/XChainAttestations.h>
+#include <xrpl/protocol/XRPAmount.h>
 #include <xrpl/protocol/digest.h>
 #include <xrpl/protocol/st.h>
 #include <unordered_map>
diff --git a/src/xrpld/core/Config.h b/src/xrpld/core/Config.h
index 16950901f0f..37a853483d2 100644
--- a/src/xrpld/core/Config.h
+++ b/src/xrpld/core/Config.h
@@ -21,10 +21,10 @@
 #define RIPPLE_CORE_CONFIG_H_INCLUDED
 
 #include <xrpl/basics/BasicConfig.h>
-#include <xrpl/basics/FeeUnits.h>
 #include <xrpl/basics/base_uint.h>
 #include <xrpl/beast/net/IPEndpoint.h>
 #include <xrpl/beast/utility/Journal.h>
+#include <xrpl/protocol/FeeUnits.h>
 #include <xrpl/protocol/SystemParameters.h>  // VFALCO Breaks levelization
 
 #include <boost/beast/core/string.hpp>
diff --git a/src/xrpld/ledger/OpenView.h b/src/xrpld/ledger/OpenView.h
index bd8627a18b2..c8e1911bf96 100644
--- a/src/xrpld/ledger/OpenView.h
+++ b/src/xrpld/ledger/OpenView.h
@@ -23,7 +23,7 @@
 #include <xrpld/ledger/RawView.h>
 #include <xrpld/ledger/ReadView.h>
 #include <xrpld/ledger/detail/RawStateTable.h>
-#include <xrpl/basics/XRPAmount.h>
+#include <xrpl/protocol/XRPAmount.h>
 
 #include <boost/container/pmr/monotonic_buffer_resource.hpp>
 #include <boost/container/pmr/polymorphic_allocator.hpp>
diff --git a/src/xrpld/ledger/ReadView.h b/src/xrpld/ledger/ReadView.h
index 50f1a7d98c1..00d29e4281c 100644
--- a/src/xrpld/ledger/ReadView.h
+++ b/src/xrpld/ledger/ReadView.h
@@ -21,12 +21,11 @@
 #define RIPPLE_LEDGER_READVIEW_H_INCLUDED
 
 #include <xrpld/ledger/detail/ReadViewFwdRange.h>
-#include <xrpl/basics/FeeUnits.h>
 #include <xrpl/basics/IOUAmount.h>
-#include <xrpl/basics/XRPAmount.h>
 #include <xrpl/basics/chrono.h>
 #include <xrpl/beast/hash/uhash.h>
 #include <xrpl/beast/utility/Journal.h>
+#include <xrpl/protocol/FeeUnits.h>
 #include <xrpl/protocol/Fees.h>
 #include <xrpl/protocol/Indexes.h>
 #include <xrpl/protocol/LedgerHeader.h>
@@ -35,6 +34,7 @@
 #include <xrpl/protocol/STAmount.h>
 #include <xrpl/protocol/STLedgerEntry.h>
 #include <xrpl/protocol/STTx.h>
+#include <xrpl/protocol/XRPAmount.h>
 #include <cassert>
 #include <cstdint>
 #include <memory>
diff --git a/src/xrpld/ledger/detail/ApplyStateTable.h b/src/xrpld/ledger/detail/ApplyStateTable.h
index d1616d095e5..e4c8b9ad656 100644
--- a/src/xrpld/ledger/detail/ApplyStateTable.h
+++ b/src/xrpld/ledger/detail/ApplyStateTable.h
@@ -23,10 +23,10 @@
 #include <xrpld/ledger/OpenView.h>
 #include <xrpld/ledger/RawView.h>
 #include <xrpld/ledger/ReadView.h>
-#include <xrpl/basics/XRPAmount.h>
 #include <xrpl/beast/utility/Journal.h>
 #include <xrpl/protocol/TER.h>
 #include <xrpl/protocol/TxMeta.h>
+#include <xrpl/protocol/XRPAmount.h>
 #include <memory>
 
 namespace ripple {
diff --git a/src/xrpld/ledger/detail/ApplyViewBase.h b/src/xrpld/ledger/detail/ApplyViewBase.h
index 8305731b29e..8cc38e41430 100644
--- a/src/xrpld/ledger/detail/ApplyViewBase.h
+++ b/src/xrpld/ledger/detail/ApplyViewBase.h
@@ -24,7 +24,7 @@
 #include <xrpld/ledger/OpenView.h>
 #include <xrpld/ledger/ReadView.h>
 #include <xrpld/ledger/detail/ApplyStateTable.h>
-#include <xrpl/basics/XRPAmount.h>
+#include <xrpl/protocol/XRPAmount.h>
 
 namespace ripple {
 namespace detail {