Do you mean, how do you post a tag at this URL in the first place, or how do you find out what the URL is for a Subversion tag?Either way, the answer is that this is just a mirror of what's in the Git repo. So if you make a tag called "blah-blah-blah" using Git and push it, then there will automatically be a path available to Subversion clients (but not web browers) at:https://github.com/CESM-Development/cime/tags/blah-blah-blahThis is not really documented on GitHub's site itself, although I think it was not to hard to figure out where this directory was by using Google or "svn ls". Note that support for tags seems to have been one of the last things added by GitHub, and it doesn't get anything more than a half sentence in an update at the very end of this blog post:https://github.com/blog/966-improved-subversion-client-supportIt's pretty much analogous to how branches are described on that post, though.