HP OpenVMS Guide to System Security: OpenVMS Version 8.4 > Appendix A Assigning Privileges
The GRPNAM privilege lets the user's process bypass discretionary access controls on the system logical name table in order to insert names into (and delete names from) the logical name table of the group to which the process belongs by the use of the Create Logical Name ($CRELNM) and Delete Logical Name ($DELLNM) system services.
In addition, the privileged process can issue the DCL commands ASSIGN and DEFINE to add names to the group logical name table and the DCL command DEASSIGN to delete names from the table. The privilege allows the use of the /GROUP qualifier with the DCL commands MOUNT and DISMOUNT (as well as the system services $MOUNT and $DISMOUNT) when sharing volumes among group members.
Do not grant this privilege to all users of the system because it allows the user's process to create an unlimited number of group logical names. When unqualified users have the unrestricted ability to create group logical names, excessive use of system dynamic memory can degrade system performance. In addition, a process with the GRPNAM privilege can interfere with the activities of other processes in the same group by creating definitions of commonly used logical names such as SYS$SYSTEM.