what is the meaning of LVM id in ks.cfg

[Aldo Foot <lunixer gmail com>]

Looking at this article:  http://kbase.redhat.com/faq/docs/DOC-5511

What is the meaning or purpose of the "01" in the lines
     part pv.01 --size=1 --grow
     volgroup vg_root pv.01
Is it an arbitrary number to give an id to the VG?

In my system the lines read (ks.cfg created by anaconda):
     part pv.18 --size=1 --grow
     volgroup myVG - -pesize=8192 pv.18

In some other example I see:
     part pv.6 --size=1 --grow
     volgroup someVG- -pesize=32768 root pv.6

I curious because one may want to use a ks.cfg in a brand new disk, which may
be physically different and have a different partition layout.

TIA,
~af