Understanding Revision Numbers
==============================

All revisions in the mainline of a branch will have a simple increasing
integer. (First commit gets 1, 10th commit gets 10, etc.) This makes them
fairly natural to use when you want to say "grab the 10th revision from my
branch", or "fixed in revision 3050".

For revisions which have been merged into a branch, a dotted notation is
used (eg, 3112.1.5). Dotted revision numbers have three numbers. The first
number indicates what mainline revision change is derived from. The second
number is the branch counter. There can be many branches derived from the
same revision, so they all get a unique number. The third number is the
number of revisions since the branch started. For example, 3112.1.5 is the
first branch from revision 3112, the fifth revision on that branch.

Revisions are numbered in a stable way, such that if two branches have the
same revision in their mainline, all revisions in the ancestry of that
revision will have the same revision numbers. (So if Alice and Bob's
branches agree on revision 10, they will agree on all revisions before
that.) Future merges will not change revision numbers. However doing
``bzr pull`` can change revision numbers, because it changes the
mainline revisions.


bzr versions < 1.2
------------------
Versions prior to bzr 1.2 used a slightly different algorithm. Some nested
branches would get extra numbers (such as 1.1.1.1.1) rather than the
simpler 3-number system.

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