Author: larry Date: Wed Aug 29 03:57:51 2007 New Revision: 14441 Modified: doc/trunk/design/syn/S02.pod
Log: Clarification of Ps/Pe vs Bidi requested by sunnavy++ Modified: doc/trunk/design/syn/S02.pod ============================================================================== --- doc/trunk/design/syn/S02.pod (original) +++ doc/trunk/design/syn/S02.pod Wed Aug 29 03:57:51 2007 @@ -14,7 +14,7 @@ Date: 10 Aug 2004 Last Modified: 29 Aug 2007 Number: 2 - Version: 113 + Version: 114 This document summarizes Apocalypse 2, which covers small-scale lexical items and typological issues. (These Synopses also contain @@ -80,11 +80,16 @@ as opening brackets. This includes the second section of the Unicode BidiMirroring data table, as well as C<U+201A> and C<U+201E>. -If a character is already used in Ps/Pe mappings, then its entry in -BidiMirroring is ignored. Therefore C<U+298D> maps to C<U+298E>, -not C<U+2990>, and C<U+298E> itself is not a valid bracket opener. +If a character is already used in Ps/Pe mappings, then any entry +in BidiMirroring is ignored (both forward and backward mappings). +For any given Ps character, the next Pe codepoint (in numerical +order) is assumed to be its matching character even if that is not +what you might guess using left-right symmetry. Therefore C<U+298D> +maps to C<U+298E>, not C<U+2990>, and C<U+298F> maps to C<U+2990>, +not C<U+298E>. Neither C<U+298E> nor C<U+2990> are valid bracket +openers, despite having reverse mappings in the BidiMirroring table. -The C<U+301D> has two closing alternatives, C<U+301E> and C<U+301F>; +The C<U+301D> codepoint has two closing alternatives, C<U+301E> and C<U+301F>; Perl 6 only recognizes the one with lower code point number, C<U+301E>, as the closing brace. This policy also applies to new one-to-many mappings introduced in the future.