Não tanto quanto eu sei (mas como @sputnick aponta , eu não sei muito), mas você pode analisá-lo:
man chmod | grep -C 5 'a+x'
Eu recomendaria o uso de uma string que realmente existe na página de manual, algo como:
$ man chmod | grep -C 5 set-user-ID
traversals.
SETUID AND SETGID BITS
chmod clears the set-group-ID bit of a regular file if the file's group ID does not match the
user's effective group ID or one of the user's supplementary group IDs, unless the user has appro‐
priate privileges. Additional restrictions may cause the set-user-ID and set-group-ID bits of
MODE or RFILE to be ignored. This behavior depends on the policy and functionality of the under‐
lying chmod system call. When in doubt, check the underlying system behavior.
chmod preserves a directory's set-user-ID and set-group-ID bits unless you explicitly specify oth‐
erwise. You can set or clear the bits with symbolic modes like u+s and g-s, and you can set (but
not clear) the bits with a numeric mode.
RESTRICTED DELETION FLAG OR STICKY BIT
The restricted deletion flag or sticky bit is a single bit, whose interpretation depends on the