User identifier
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... The AUTH_SYS flavor provides a UNIX-style user identifier, group
identifier, and an array of supplemental group identifiers ...
... authentication, the server gets the
client's effective user identifier, effective group identifier and
supplemental group ...
...
For those sites that do not implement a consistent user identifier
and group identifier space, NFS ...
... identity mapping is
more operating system independent than the user identifier and group
identifier mapping in AUTH_SYS. Also, because the authentication ...