Meaning of allowed_requests keys for SSH config

Question

I need to set the allowed_requests (-p) option for the ForceCommand keyword on ssh config file. /usr/lib/openssh/sftp-server -Q requests returns the list of available values.

open
close
read
write
lstat
fstat
setstat
fsetstat
opendir
readdir
remove
mkdir
rmdir
realpath
stat
rename
readlink
symlink
posix-rename
statvfs
fstatvfs
hardlink
fsync
lsetstat
limits
expand-path

Where can I find the meaning of each option?

I need to restrict access for a user and I'd like to understand what the tutorial I'm following is setting.

Answer 1

You can find almost each option explanation over here: https://github.com/mscdex/ssh2/blob/master/SFTP.md

Good luck with the tutorial!