+refspec::
+ A refspec is used by fetch and push to describe the mapping
+ between remote ref and local ref. They are combined with
+ a colon in the format <src>:<dst>, preceded by an optional
+ plus sign, +. For example:
+ `git fetch $URL refs/heads/master:refs/heads/origin`
+ means "grab the master branch head from the $URL and store
+ it as my origin branch head".
+ And `git push $URL refs/heads/master:refs/heads/to-upstream`
+ means "publish my master branch head as to-upstream master head
+ at $URL". See also gitlink:git-push[1]
+