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
'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\
and dereference the tag recursively until a non-tag object is
found.
-'git-rev-parse' also accepts a prefix '{caret}' to revision parameter,
-which is passed to 'git-rev-list'. Two revision parameters
-concatenated with '..' is a short-hand for writing a range
-between them. I.e. 'r1..r2' is equivalent to saying '{caret}r1 r2'
+* 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
G H I J
\ / \ /
D E F
- \ | /
- \ | /
- \|/
+ \ | / \
+ \ | / |
+ \|/ |
B C
\ /
\ /
J = F^2 = B^3^2 = A^^3^2
+SPECIFYING RANGES
+-----------------
+
+History traversing commands such as `git-log` operate on a set
+of commits, not just a single commit. To these commands,
+specifying a single revision with the notation described in the
+previous section means the set of commits reachable from that
+commit, following the commit ancestry chain.
+
+To exclude commits reachable from a commit, a prefix `{caret}`
+notation is used. E.g. "`{caret}r1 r2`" means commits reachable
+from `r2` but exclude the ones reachable from `r1`.
+
+This set operation appears so often that there is a shorthand
+for it. "`r1..r2`" is equivalent to "`{caret}r1 r2`". It is
+the difference of two sets (subtract the set of commits
+reachable from `r1` from the set of commits reachable from
+`r2`).
+
+A similar notation "`r1\...r2`" is called symmetric difference
+of `r1` and `r2` and is defined as
+"`r1 r2 --not $(git-merge-base --all r1 r2)`".
+It it the set of commits that are reachable from either one of
+`r1` or `r2` but not from both.
+
+Here are a few examples:
+
+ D A B D
+ D F A B C D F
+ ^A G B D
+ ^A F B C F
+ G...I C D F G I
+ ^B G I C D F G I
+
Author
------
Written by Linus Torvalds <torvalds@osdl.org> and