Peter Kirk wrote:
> The Unicode standard, 4.0 section 15.2, specifies ZWJ and ZWNJ as the
> characters to use for promoting or inhibiting ligatures. But the text
> seems to assume that the characters being ligated are base
> characters. A
> problem arises when ZWJ or ZWNJ is inserted between combining
> marks to
> promote or inhibit ligation: as non-combining control
> characters these
> characters break the combining sequence, such that the following
> combining mark forms a defective combining sequence whose
> rendering is undefined.
I have suggested that ZWJ and ZWNJ be made combining characters
of class 0 (which would be permissibly stable), so that ZWJ and
ZWNJ can occur between a base character and combining
characters (needed for Khmer) or between Hebrew combining
characters (that are in canonical order without the ZWJ/ZWNJ).
Current use (between combining sequences) would fall under
the special case of ZWJ/ZWNJ being at the end of a combining
sequence (rather than after it).
/kent k
