Beginning with OES 2015, the zNW_id_u union has been added to XAttr NDK, and it contains the actual user identity information (SID for Active Directory and GUID for eDirectory).
typedef union zNW_id_u { SID_t aduser; GUID_t ediruser; } zNW_id_u;
Specifies the Active Directory user’s SID.
Specifies the eDirectory user’s GUID.