<p>Things like <code>$log$</code> and <code>$version$</code> which add data upon check-in to the file. I'm interested in seeing the other ones and what information they can provide, but I can't get much info unless I know what they are called.</p>

Both Subversion and CVS call them
```
Keywords
```
.
Have a look in the SVN manual here
(scroll down to
svn:keywords
) or
here for CVS
.