[b0in]

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.

[Postosuchus]

Pretty interesting. I guess it was way later, when they came up with the SUID semantics and appropriated the first character for symlinks (l) or setuid binaries (s)...