The Tavern

what is the tag major version mean?

old version? like 0.12?

IIRC, the major version goes up when save file compatibility is broken and stays the same when save files between versions are compatible.

It's code that will be removed when save compatibility is broken. This hasn't happened for a while, since lots of changes can be made without breaking compatibility by using minor version tags - the last major version increase was in August 2012. There's a good blog post that talks about tags and save compatibility in a bit of detail here.