[luatex] a question about the names \Umathcharnumdef etc

[jfbu]

Hi,

as people reported problems with mathastext under lualatex I have become aware
that \luatexUmathcharnumdef etc... have been removed and \Umathcharnumdef etc...
must be used  instead.

as I didn't find the info immediately I am asking here: how should I test
(version number, date etc...)
when one should use \luatexUmathcharnumdef and
when on should use \Umathcharnumdef ?

or perhaps \Umathcharnumdef was always ok ?

I would like to not break people's old installation thus I would be
glad to use \Umathcharnumdef  if I am told it works with all earlier lualatex

best wishes

Jean-François