I don't know what Microsoft does, but at least, combining 25CC with a combining diacritic DOES work in current versions of Internet Explorer.
But as it is known that this could cause a problem, for example when rendering charts on the web, a simple solution generally adopted involves the use of a more natural arbitrary base character, and some other presentation style (such as colored backgrounds). See examples like there (diacritics are shown with a natural base character, but a consistant blue background for all tables): - http://fr.wikipedia.org/wiki/Table_des_caract%C3%A8res_Unicode/U0300 (it uses the Latin letter 'o' for diacritics used with the Latin script) - http://fr.wikipedia.org/wiki/Table_des_caract%C3%A8res_Unicode/U0590 (it uses the Hebrew letter SHIN for all Hebrew diacritics) - http://fr.wikipedia.org/wiki/Table_des_caractères_Unicode/U0600 (another Arabic letter is used for all Arabic diacritics) And so on... Additionally, the controls are shown with a red background, and format controls are within a box with a dashed border. Unallocated codepoints are shown with a grey background. There's no risk of confusion with a true dotted circle symbol. But the Unicode and ISO/IEC 10646 charts (in PDFs or printed books) need to be monochrome, so instead of using distinctive color background, it's normal that they use a symbol that cannot be exactly similar to an encoded character. Philippe. "Vincent Setterholm" <[email protected]> wrote: > > I've tried using 25CC. The problem I'm running into is that the font designer > can make marks combine with 25CC just fine but then Microsoft simply ignores > the look-up tables that shape these combinations and inserts their own dotted > circle (or circles - one per combining mark) anyway. > > I don't know what effect using a 'symbol' for a letter has on indexing or > searching or line/word breaking because I haven't even gotten so far as to > get the display to look right, but I'm guessing there'd also be an advantage > to such a character having letter semantics. > > This need to display marks, well-formed on a generic base, is a really common > phenomenon. Countless grammars and other philology and linguistics > books/articles/etc. have to represent these types of patterns. I think there > needs to be an official solution for placing marks on a generic base that > behaves like a letter - something documented so that future font designers > can support this and so that the technology providers like Microsoft, ICU, > etc. have clear directions on how to support this. > > If using 25CC really is the answer, then let's publish that solution as part > of the Unicode Standard so that all font designers can follow this convention > and so that we can have some hope of companies like Microsoft supporting the > standard. > > ________________________________________ > From: Otto Stolz [[email protected]] > Sent: Saturday, June 26, 2010 8:03 AM > To: Vincent Setterholm > Cc: '[email protected]' > Subject: Re: Generic Base Letter > > Hi Vincent Setterholm, > > you have been asking: > > What I'd like to see is a code point for a generic base character > > You could try U+25CC DOTTED CIRCLE, though the reference glyph > for this cgaracter is larger than the dotted circles used to > attach the various combining marks, in their respective reference > glyphs. > > Best wishes, > Otto Stolz > > >
