[isabelle-dev] NEWS: High-quality blackboard-bold symbols

[Makarius]

*** Document preparation ***

* High-quality blackboard-bold symbols from font "txmia" (package
"txfonts"), for A..Z.


This refers to Isabelle/b138cdd22cfb.

That is a spin-off from the Z Notation support, because that requires
additional blackboard-bold symbols.

I've always found the approximation from AMS rather crude, and actually Joris
van der Hoeven (TeXmacs) agrees with that, see
https://www.texmacs.org/joris/fontart/fontart.html

The ultimate source for LaTeX symbols is
https://tug.ctan.org/info/symbols/comprehensive/symbols-a4.pdf --- table 316
on page 123 was relevant for the hint on txmia/txfonts.


	Makarius