How are DVDs identified by anaconda?

[Chris <chris1 noreply googlemail com>]

I've built a Fedora 9 based installation DVD using revisor and it's
working fine but I needed to add some files to the root directory on
the DVD. I've been able to do this using a program called IsoMaster
which opens the ISO, allows me to add files, then rebuilds the ISO.
This works fine except that it's a manually GUI-only operation and I
need to script it.

So now in my script I mount the ISO as a loop device, add the files,
then recreate the ISO using genisoimage. This seems to work OK at
first, when I boot from the DVD I get the boot menu and can choose the
install option but when anaconda starts up it tells me to insert the
correct DVD.

So my question is, how is the DVD identified? I thought it was by the
ISO label but I've been careful to make sure that this is preserved to
be the same as that generated by revisor - although I will go and
double-check this.

I'm sure this must be possible because it works when I do it manually
using IsoMaster, but I'm clearly going wrong somewhere.

Any suggestions welcome!

Thanks, Chris.