On Fri, 16 Feb 2018 15:25:22 -0800 James Kass via Unicode <[email protected]> wrote:
> Some people studying Han characters use the IDCs to illustrate the > ideographs and their components for various purposes. For example: > > U-0002A8B8 𪢸 ⿰土土 > U-0002A8B9 𪢹 ⿰土凡 > U-0002A8BA 𪢺 ⿱夂土 > U-0002A8BB 𪢻 ⿰土亡 > U-0002A8BC 𪢼 ⿰土无 > U-0002A8BD 𪢽 ⿰土冇 > U-0002A8BE 𪢾 ⿰土攴 > U-0002A8BF 𪢿 ⿰土月 > U-0002A8C0 𪣀 ⿰土化 > U-0002A8C1 𪣁 ⿰土丰 > > It would be probably be disconcerting if the display of those > sequences changed into their respective characters overnight. And it would be extremely disconcerting if this post was suddenly rendered in mediaeval black letters, but in theory that could happen. One can argue that once the compound ideograph have been encoded, the IDS should no longer be interpreted. However, I think it will be difficult to do this in practice. > Such > usage might be limited to scholars and students, and a desire for > default composition might outweigh scholarly concerns, The lack of mix and match control of the font choices for 'plain text' presentations is disappointing. We probably need a pair of OpenType features, one to discourage and one to encourage interpretation of IDSes. For web pages and PDFs one should be able to specify the font or fonts, and OpenType features are increasingly being supported. > but IMHO to say > that 'doing it reasonably well at the font level would be a lot of > work' is a vast understatement. That was my first thought, but I had worried that I might have been overestimating. For the examples you give above, I strongly suspect that Code2001 already contains the requisite glyph halves. There is another possible use of the latitude given by TUS 5.0 to 10.0 and possibly earlier. I can certainly imagine a case where someone writes a font so that an unencoded character may be manipulated like any other character. He has two choices - he can put it in the PUA, or he can make it the ligature for the IDS. If he chooses the former, and then the text and font are separated, the recipient of the text is left with tofu for the character. If he chooses the latter, the recipient of the text would at least have the IDS. I think the latter outcome is the better outcome. Richard.
