This is the "branch reset" pattern, which has the special property
that the capture buffers are numbered from the same starting point
-in each branch. It is available starting from perl 5.10.
+in each alternation branch. It is available starting from perl 5.10.
-Normally capture buffers in a pattern are numbered sequentially,
-from left to right. Inside this construct that behaviour is
-overridden so that the capture buffers are shared between all the
-branches and take their values from the branch that matched.
+Capture buffers are numbered from left to right, but inside this
+construct the numbering is restarted for each branch.
The numbering within each branch will be as normal, and any buffers
following this construct will be numbered as though the construct