diff --git a/body.adoc b/body.adoc
index 1b6aec4..28c4747 100644
--- a/body.adoc
+++ b/body.adoc
@@ -238,7 +238,7 @@ and software should ignore but preserve any fields that it does not recognize.
 [NOTE]
 [%unbreakable]
 ====
-_Logical entry 0, accessed via `sireg*` when `siselect`=0x200, is always the physical entry preceding the WRPTR entry ((WRPTR-1) % depth), where depth = 2^(DEPTH+4)^._
+_Logical entry 0, accessed via `sireg*` when `siselect`=0x200, is always the physical buffer entry preceding the WRPTR entry.  More generally, the physical buffer entry Y associated with logical entry X can be determined using the formula Y = (WRPTR - X - 1) % depth, where depth = 2^(DEPTH+4)^._
 ====
 [NOTE]
 [%unbreakable]