version (`%A`) and the other branches' version (`%B`). These
three tokens are replaced with the names of temporary files that
hold the contents of these versions when the command line is
-built.
+built. Additionally, %L will be replaced with the conflict marker
+size (see below).
The merge driver is expected to leave the result of the merge in
the file named with `%A` by overwriting it, and exit with zero