@LordMike Is there a problem with this PR?

Hi, sorry,..

I have a general issue with PR's because I don't have the knowledge required to verify them.

We can try though..

• Have you verified the changes? How?
• Did you check with other tools / specs / other sources to verify that this is the "correct" behaviour?

Joliet is an extension to Iso9660, so that's why ISOs can come either with or without the joliet data.
I don't see how leaving in the Joliet specific data, that being the supplementary volume descriptor, in any way makes sense (in fact, you can find plenty of ISOs that don't have it, mostly ones that target older systems).
In this case I was dealing with something related to the PS2, where the loader would reject the ISO if it had the Joliet data (likely didn't support it) and other ISOs that did work did not have that extra data.
If you google around a bit you can find a few things describing lack of support (notably some Linux distro) for Joliet, and the like.

From https://wiki.sleuthkit.org/index.php?title=ISO9660:
"Supplementary volume descriptors are very similar to primary volume descriptors. The main difference is that supplementary volume descriptors can store file names in other encodings, such as Unicode and mixed case.

ISO9660 with "Joliet" support use the secondary volume descriptor to reference a duplicate directory tree that contains the Unicode names. ISO9660 with "Rock Ridge" adds additional metadata into the directory entries to store permissions and other metadata. These can exist in either the primary or secondary volume descriptor trees."

From https://wiki.osdev.org/ISO_9660:
"Joliet was defined by Microsoft Inc. to allow for filenames with up to 64 UCS-2 characters (16 bit). It is implemented as separate tree of Directory Records which begins by a root record in a Supplementary Volume Descriptor. That descriptor is similar to a Primary Volume Descriptor, but has a Type Code of 2."

Ok, so the "Joliet" directory tree is a complete duplicate? Everything in the main tree must also exist in the duplicated Unicode tree?

... that could pose a number of issues.. Damn. :P