Comment # 4 on bug 964971 from Noel Power

(In reply to Christian Boltz from comment #3)
> Seth Arnold asked me to forward this question to you:
> 
> I -do- have to ask, if this is the first time they actually need it, could
> they store their acls in samba.NTACL instead? why does their acl have to
> live in the security. xattr namespace?

so afaics this functionality has been in place for quite some time, could
another namespace be used ? I suppose it could, but even so that would not
happen in the short term (so we suse at least would need a patch), making such
a change would require some sort of migration path. As I understand it (from
looking back through the archives) one of the original reasons for choosing the
security namepace was there was a hope to eventually implement a LSM module
that understands these ACLs (and move away from interpreting them in smbd)
The historical discussion is here
http://samba-technical.samba.narkive.com/eHtOW8DE/nt-acls-using-the-security-namespace-for-ntacl-considered-improper
where it seems the decision was to keep the security namespace. Hope this
answers your question