[XeTeX] Math class initialization in Unicde-aware engine

Doug McKenna doug at mathemaesthetics.com
Mon Dec 2 06:56:26 CET 2019

Joseph Wright wrote:

>| Er, I thought the README was reasonably clear, ah well!

Here's an example of something that's not so clear to me.

The README.md file displayed at



- \lccode and/or \uccode for non-letter code points
  for which an upper or lower case mapping is given

The problem with this is that earlier, it is stated that all combining mark code points (class code starting with 'M' in the UnicodeData.txt file) are to be considered letters (\catcode set to 11).  So there's an ambiguity here that needs clearing up.  Does the above apply to combining mark code points or not?

It may be that none of the combining marks in the data file have any case mappings, but there's no guarantee that is true.  So the question is, if a combining mark has an uppercase or lowercase mapping, does that get installed in \lccode and/or \uccode?

Also, there's a confusing typo ("can"?) in

- \lccode and \uccode for all of class "Lt" (title
  case letters) to the lower can upper case mappings
  (or if not given to the code point itself)

Should "can' be "and/or"?

Doug McKenna

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