USE userlist ORDER username                   && Open the user table
cName=SUBSTR(SYS(0),AT("#",SYS(0))+2,15)      && Use SYS(0) to get current 
                                              && user network user ID
IF SEEK(cName,"userlist")                     && If this user is OK
   RETURN .T.                                 && ...then Return True (OK)
ELSE
   RETURN .F.                                 && ...else Return False (Not OK)
ENDIF