Using conditional Z codes in local FRT

Question

I would like to do something like the following in my local FRT, but cannot find enough documentation to know how to do it:

If the zvar "version-name"  = "readers version", then output \pb. Else, output \zNeedOddPage
I found enough documentation on this subject on github and PTXprint technical reference to know it should be possible, but with no examples, it is hard to know what to do.

Answer 1

You can't easily check the content of zvars, at the moment, sorry, it is only testing to see if the value has been set or unset (and what set-but-empty counts as).
This might work, it takes advantage of \zifvarset setting \tmp to be the variable's value internally, if it is configured...

\let\tmp\empty
\def\readersversion{readers version}
\zifvarset|version-name\*
\ifx\tmp\readersversion
%READERS VERSION STUFF HERE
\else
% Default case here.
\fi