Can anyone provide a reference on what those file permissions mean? I can make a guess but when I searched around, could not find anything about unix v2 permissions. ls output looks so familiar, except for the sdrwrw!

Someone in the mailing list thread linked the man pages that they were able to extract out

https://gitlab.com/segaloco/v1man/-/blob/master/man1/stat.1?...

for sdrwrw:

- column 1 is s or l meaning small or large

- column 2 is d, x, u, -; meaning directory, executable, setuid, or nothing.

- the rest are read-write bits for owner and non-owner.