Is that a bug between xymatrix, the input command and .sty file?

I have a problem compiling the following document.

First, I have a file macros.sty that consists of :

\newcommand{\test}{
\xymatrix@R=0mm{x}
}

Then, I have an auxiliary file out.aux that consists of :

\test

Finally, the main file is :

\documentclass{article}
\usepackage[all]{xy}
\usepackage{macros}
\begin{document}
\input{out.aux}
\end{document}

The error message is :

./out.aux:1: Undefined control sequence.
\xymatrixrowsep@ \dimen@ii

Note that if you remove the R=0mm, the problem no longer holds.

Is that a bug ?

It is very strange because I remember to have already used a command similar to \test in an input file without any problem.

Does it come from my distribution ?

Thank you :)

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As a side note, you might consider accepting some of the answers from your previous questions. This will improve your 'acceptance rate', and may influence how many people answer your current question :) –  cmhughes Oct 18 '11 at 15:19
I agree with you --- but, actually, some of my questions didn't get a satisfying answer, imo. (Even though these answers are interesting and nice) –  Colas Oct 18 '11 at 16:03