Re: [PATCH 3/5] git-log.txt: fix description of <since>..<until>

Jonathan Nieder wrote:

What's the difference between a revision and a commit?  The definition
in gitglossary(7) only confuses me.

What's so confusing about it?

commit:: As a noun: A single point in the Git history; the entire
history of a project is represented as a set of interrelated commits.
The word "commit" is often used by Git in the same places other
revision control systems use the words "revision" or "version". Also
used as a short hand for commit object.

revision:: A particular state of files and directories which was
stored in the object database. It is referenced by a commit object.

-- 8< --

There a reference to "revision" in the "commit" description which
might be misleading.

Otherwise, these are quite accurate.  master~3:README is a valid revision,
but not a commit, for instance.  Another problem with the word commit
is that it doesn't encapsulate ranges like 'master~3..HEAD'.  It would
probably help to add the terms "commitish" and "treeish" to the
glossary to refer to "rev specs" (those in revisions.txt) that resolve
to commits or trees.  I'll give you two simple examples:

1. In 'git show master:README', master is a treeish and master:README
is a blob.  If we were to say 'git blame master: -- README', it would
error out because master: is not a commitish, but a treeish.

2. In 'git log master~3.. -- README', master~3.. is a commitish.  In
general, log can take only rev specs that resolve to a commits.
Although 'git log master:' doesn't error out, it doesn't make any
sense either.  Perhaps we should tighten it?