{'foobar.PL' => 'foobar'}
The *.PL files are expected to produce output to the target files
-themselves.
+themselves. If multiple files can be generated from the same *.PL
+file then the value in the hash can be a reference to an array of
+target file names. E.g.
+
+ {'foobar.PL' => ['foobar1','foobar2']}
=item PM