A revision parameter typically, but not necessarily, names a
commit object. They use what is called an 'extended SHA1'
-syntax.
+syntax. Here are various ways to spell object names. The
+ones listed near the end of this list are to name trees and
+blobs contained in a commit.
* The full SHA1 object name (40-byte hexadecimal string), or
a substring of such that is unique within the repository.
name the same commit object if there are no other object in
your repository whose object name starts with dae86e.
+* An output from `git-describe`; i.e. a closest tag, followed by a
+ dash, a `g`, and an abbreviated object name.
+
* A symbolic ref name. E.g. 'master' typically means the commit
object referenced by $GIT_DIR/refs/heads/master. If you
happen to have both heads/master and tags/master, you can
explicitly say 'heads/master' to tell git which one you mean.
+ When ambiguous, a `<name>` is disambiguated by taking the
+ first match in the following rules:
+
+ . if `$GIT_DIR/<name>` exists, that is what you mean (this is usually
+ useful only for `HEAD`, `FETCH_HEAD` and `MERGE_HEAD`);
+
+ . otherwise, `$GIT_DIR/refs/<name>` if exists;
+
+ . otherwise, `$GIT_DIR/refs/tags/<name>` if exists;
+
+ . otherwise, `$GIT_DIR/refs/heads/<name>` if exists;
-* A suffix '@' followed by a date specification enclosed in a brace
+ . otherwise, `$GIT_DIR/refs/remotes/<name>` if exists;
+
+ . otherwise, `$GIT_DIR/refs/remotes/<name>/HEAD` if exists.
+
+* A ref followed by the suffix '@' with a date specification
+ enclosed in a brace
pair (e.g. '\{yesterday\}', '\{1 month 2 weeks 3 days 1 hour 1
second ago\}' or '\{1979-02-26 18:30:00\}') to specify the value
of the ref at a prior point in time. This suffix may only be
'rev{caret}0' means the commit itself and is used when 'rev' is the
object name of a tag object that refers to a commit object.
-* A suffix '~<n>' to a revision parameter means the commit
+* A suffix '{tilde}<n>' to a revision parameter means the commit
object that is the <n>th generation grand-parent of the named
commit object, following only the first parent. I.e. rev~3 is
- equivalent to rev{caret}{caret}{caret} which is equivalent to\
- rev{caret}1{caret}1{caret}1.
+ equivalent to rev{caret}{caret}{caret} which is equivalent to
+ rev{caret}1{caret}1{caret}1. See below for a illustration of
+ the usage of this form.
* A suffix '{caret}' followed by an object type name enclosed in
brace pair (e.g. `v0.99.8{caret}\{commit\}`) means the object
and dereference the tag recursively until a non-tag object is
found.
+* A suffix ':' followed by a path; this names the blob or tree
+ at the given path in the tree-ish object named by the part
+ before the colon.
+
+* A colon, optionally followed by a stage number (0 to 3) and a
+ colon, followed by a path; this names a blob object in the
+ index at the given path. Missing stage number (and the colon
+ that follows it) names an stage 0 entry.
+
Here is an illustration, by Jon Loeliger. Both node B and C are
a commit parents of commit node A. Parent commits are ordered
left-to-right.