Why are file names limited to 12 characters long?

[rubixcube6]

ERROR: Name entry for file 'DEBUGTEXTURE.TIM' is more than 12 characters long on line 8.

the ISO 9660 standard says this (https://www.ecma-international.org/publications-and-standards/standards/ecma-119/):

At Level 1 the following restrictions shall apply to a volume identified by a Primary Volume Descriptor or by a
Supplementary Volume Descriptor:

- each file shall consist of only one File Section;
- a File Name shall not contain more than eight d-characters or eight d1-characters;
- a File Name Extension shall not contain more than three d-characters or three d1-characters;
- a Directory Identifier shall not contain more than eight d-characters or eight d1-characters.

At Level 1 the following restrictions shall apply to a volume identified by an Enhanced Volume Descriptor:
- each file shall consist of only one File Section.

10.2 Level 2
At Level 2 the following restriction shall apply:
- each file shall consist of only one File Section

10.3 Level 3
- At Level 3 no restrictions shall apply.

Level 2 has a 31 character limit.

I can confirm that real PSX hardware can read a Level 2 ISO 9660 disk.

If I build a CD with mkpsxiso, then extract the contents to a folder, I can create a new image from that (using imgburn) including a .TIM file with 16 characters in the file name. I tried it in an emulator and the texture loaded without issues. I burnt that same image to a CDR and tried it in my real PlayStation and it loaded the texture and displayed it just fine.