Now then, that is stretching my memory a bit.
It has to do with keyword substitution (
http://svnbook.red-bean.com/en/1.7/svn.a...words.html), Nicholas Lee set this up when we moved to Subversion from CVS many years ago. As I remember the string
$Id$
needs to be inserted at the beginning of the file and then subversion will substitute Id with the details of that revision. Looking at it that needs to be within a comment so
/* $Id$ */
but that's about as far as I remember. These days I only use Git as it does so much more and so much better so my subversion knowledge is sketchy at best.
Tim