defined case folding by unicode support level

Author: TimToady

S02-bits.pod

@@ -14,7 +14,7 @@ Synopsis 2: Bits and Pieces
     Created: 10 Aug 2004
 
     Last Modified: 9 Jan 2011
-    Version: 232
+    Version: 233
 
 This document summarizes Apocalypse 2, which covers small-scale
 lexical items and typological issues.  (These Synopses also contain

S05-regex.pod

@@ -218,7 +218,10 @@ The single-character modifiers also have longer versions:
 
 The C<:i> (or C<:ignorecase>) modifier causes case distinctions to be
 ignored in its lexical scope, but not in its dynamic scope.  That is,
-subrules always use their own case settings.
+subrules always use their own case settings.  The amount of case folding
+depends on the current context.  In byte and codepoint mode, level 1 case folding
+is required (as defined in TR18 section 2.4).  In grapheme mode level 2 is
+required.
 
 The C<:ii> (or C<:samecase>) variant may be used on a substitution to change the
 substituted string to the same case pattern as the matched string.