z/OS server restrictions

Because z/OS Unix does not have a unique Base Mask ACL entry:
- The z/OS NFS Server uses the Base Group ACL entry permission value for calculating the Mask ACL entries sent to NFS Clients.
- The z/OS NFS Server fails set attribute requests containing Mask ACL entries that do not match the Base Group ACL entry. The failure returns an NFS4ERR_ATTRNOTSUPP error.
Because z/OS Unix does not have unique Default Base ACL entries:
- The z/OS NFS Server uses the Access Base ACL entries for calculating the Default Base ACL entries sent to NFS Clients (that is, the Access and Default Base ACL entries will always match).
- The z/OS NFS Server fails set attribute requests containing Default Base ACL entries that do not match the Access Base ACL entries. The failure returns an NFS4ERR_ATTRNOTSUPP error.
- Since z/OS Unix only has Default Extended ACLs, Default Base ACLs are returned by the z/OS Server if Default Extended ACLs are also present.
Because non-z/OS platforms do not have separate File and Directory Default ACLs:
- The z/OS NFS Server uses the File Default ACL entries for the NFS Default ACL entries sent to non-z/OS NFS Clients. The entries are used as both File and Directory Defaults on the non-z/OS platforms.
  The z/OS NFS Server checks all existing z/OS Unix Directory Default ACL entries to verify that they match the z/OS Unix File Default ACL entries. If the two lists do not precisely match (same entries with same permissions), the get request fails with an NFS4ERR_ATTRNOTSUPP error.
- The z/OS NFS Server uses the NFS Default ACL entries sent by a non-z/OS Client to set both the File and Directory Default ACL entries.
The z/OS NFS Server supports the File and Directory Default ACL entries as unique entries when communicating with a z/OS NFS Client. There are no ACL entry restrictions in this case.