[cjk] On modifying non-compliant fonts Re: texlive svn write access Fw: Re: revisiting ttf2tfm and dvipdfmx

[Hin-Tak Leung]

On modifying non-compliant fonts - or modifying a font for whatever reason, like 
adding a cmap to make it possible to view traditional chinese documents with 
simplified chinese glyphs -, besides the issue of know-how (not everybody should 
or would read the font format spec and hack around with a hex editor), there is 
also the issue with whether the result can be posted/shared.

There are fonts which have a GPL-like/compatible license - the Arphic fonts have 
half a dozen derivatives, differing in names and minor details and mostly 
incompatible and confusing with each other because of that; and the wcl fonts 
have derivatives which are "wrong" like having duplicate/redundant cmaps. Being 
legally allow to modify and redistribute a derivative isn't necessarily a good 
thing.

There are the restrictive ones, tied to platform, installation instance, or no 
printing/embedding.

There are also many in the middle - free use and/or re-distribution but only 
as-is. AFAIK, most of the government-issued reference fonts have this - the 
current and past Taiwanese ones and the Hong Hong ones; the IPA fonts from the 
Japanese government allows re-distribution of derivatives but have a "no 
derivative claiming the old name" clause (come to think of it, I believe the 4 
Arphic fonts also have this clause - so the way cjk/texlive is bundling the 
Type1 derivatives might be violating the license).

That's a few dozen fonts there.

Those are useable, but you live with whatever non-compliantness or 
not-fit-for-purpose-ness, there is.

Anyway, editing a font with a hex editor as a proof-of-concept that it is not 
strictly spec-compliant, I am okay with that. But creating/maintaining a 
derivative as a general and/or long-term solution, I'd prefer not to go there.

FWIW, the "abort on unknown post table version" issue (instead of "treat unknown 
as 00030000 with a warning and continue") is wide-spread, and located at - by 
grep'ing through:

texk/web2c/pdftexdir/writettf.c
texk/web2c/pdftexdir/ttf2afm.c
texk/web2c/luatexdir/font/writettf.w
texk/xdvipdfmx/src/tt_post.c
texk/dvipdfmx/src/tt_post.c

I have certainly seen the 1st and last - and got around them by editing those 2 
fonts *as a proof of concept*. I don't see why unknown post table version should 
cause an abort, given that just flipping one byte to v3 works. Obviously neither 
pdftex nor dvipdfmx are using or needing any information from the post table.

(None of the current government-issued fonts are among the 460 instances I 
mentioned - I just haven't got round to going through them yet).