Unknown GCL command id 0xF536 in real .gcx files (e.g. MGS1 USA s07b/demo.gcx)

[Greengoblin007]

While decompiling real .gcx files from MGS1 USA (PSX, Disc 2, stage s07b/demo.gcx) with the current GclCommands enum I hit:

ValueError: 62774 is not a valid GclCommands

62774 = 0xF536. The opcode appears at offset 0x1982 of s07b/demo.gcx inside an arg list right next to 0x9906 (CHARA), in a context that looks like a chara-related sub-call:

... 60 00 1b f5 36 0a 06 99 06 06 7a 05 06 66 ff 50 74 04 ...
            ^^^^^               ^^^^^
            0xF536              0x9906 (CHARA)

Adding a placeholder entry to the enum (UNK_F536 = 0xf536) is enough to round-trip the file byte-identically through decompile→compile, but I haven't been able to identify the semantic name. Filing as an issue rather than a PR so the canonical name can be used once known.

Reproducer (using upstream main + the file from disc 2):

from gcx import GcxData
from gcl_decompile import GclDecomp
g = GcxData('s07b/demo.gcx')
GclDecomp(g).decompile_gcx_file()  # raises ValueError: 62774 is not a valid GclCommands

If anyone has notes or a reference list of MGS1 GCL command IDs, I'd be happy to PR the proper enum entry.