[Acl-Devel] Section 2 or Section 3 calls?

[Kevin Goess]

Pardon if this is a dumb question, but I'm looking at doing a Perl
interface for xattr (I don't see anything more from Marc Cousin's post
in August), I noticed that there are the functions like getxattr and
setxattr in Section 2 System Calls and the functions like attr_set and
attr_get in Section 3 Library Calls.

Why would one want to the attr_* library calls rather than the *xattr
system calls?  What would be the benefit?