[texhax] an unexpected loop

[Randy Schilling]

Dear Sir,
In the code that follows \zzn is a count register,
\irrrdgts is macro containing 0 or 1,
and \vrz{0pt} is just a phantom character, a line of width 0.
The code is part of a \newif construction used with \loop...\repeat.
I apologize if I haven't  provided enough code to show the problem.

\zzn=\irrrdgts\vrz{0pt}\ifcase\zzn\rlnfalse\else\rlntrue\fi

It works with the phantom  but without the phantom,
and this is what I don.'t undersatand,  its goes into
an infinite loop.

An explanation would, as always, be very much appreciated.
Regards,
	 Randy