[XeTeX] XeTeX release notes ?

[Bruno Le Floch]

Note that the version test using \ifdim is unsafe because values are
rounded to a certain number of scaled points before being compared.

On 11/3/19 5:27 PM, Taylor, P wrote:
>                 *\ifdim \XeTeXrevision pt < 0.99999pt*

\ifdim 0.99998pt < 0.99999pt
% expected
\else
\UNEXPECTED
\fi

gives an "Undefined control sequence ... \UNEXPECTED".  Unfortunately
one needs to parse a bit more carefully the XeTeX revision, or perhaps
simply move the decimal point a bit.

\def\@XeTeX at revision@aux .#1#2{#1#2.}
\ifnum\expandafter\@XeTeX at revision@aux\XeTeXrevision<99.999pt

Bruno