What should "git rev-list origin..HEAD" return?

The git-rev-list man page shows the following commands:

$ git rev-list origin..HEAD
$ git rev-list HEAD ^origin

However, when I run the 1st command, I get the following error:

$ git rev-list origin..HEAD fatal: ambiguous argument 'origin..HEAD': unknown revision or path not in the working tree. Use '--' to separate paths from revisions, like this: 'git <command> [<revision>...] -- [<file>...]'

'origin' refers to the following remote:

$ git remote -v
origin  c:/hands_on/git/learn/clone/../repo_1 (fetch)
origin  c:/hands_on/git/learn/clone/../repo_1 (push)

Am I using the command incorrectly? Also, I thought the rev-list command takes commits as input, so I'm not clear why the man page uses 'origin' which is a remote rather. What have I misunderstood?

Solution

git-rev-parse(1) explains how the name of a remote can be used as a ref:

<refname>, e.g. master, heads/master, refs/heads/master
   A symbolic ref name. E.g.  master typically means the commit object
   referenced by refs/heads/master. If you happen to have both heads/master and
   tags/master, you can explicitly say heads/master to tell Git which one you
   mean. When ambiguous, a <refname> is disambiguated by taking the first match
   in the following rules:

    1. If $GIT_DIR/<refname> exists, that is what you mean (this is usually
    useful only for HEAD, FETCH_HEAD, ORIG_HEAD, MERGE_HEAD and
    CHERRY_PICK_HEAD);

    2. otherwise, refs/<refname> if it exists;

    3. otherwise, refs/tags/<refname> if it exists;

    4. otherwise, refs/heads/<refname> if it exists;

    5. otherwise, refs/remotes/<refname> if it exists;

    6. otherwise, refs/remotes/<refname>/HEAD if it exists.

And git-remote(1) explains what refs/remotes/<remote>/HEAD is in the description of git remote set-head:

   set-head
       Sets or deletes the default branch (i.e. the target of the symbolic-ref
       refs/remotes/<name>/HEAD) for the named remote. Having a default branch
       for a remote is not required, but allows the name of the remote to be
       specified in lieu of a specific branch. For example, if the default
       branch for origin is set to master, then origin may be specified wherever
       you would normally specify origin/master.

In other words, it uses the default branch for the remote, and you don’t appear to have one.