cperl-vc-rcs-header

cperl-vc-rcs-header is a variable defined in `cperl-mode.el'.
Its value is

("($rcs) = (' $Id$ ' =~ /(\\d+(\\.\\d+)+)/);")

Documentation:
*Special version of `vc-rcs-header' that is used in CPerl mode buffers.

You can customize this variable.