HP OpenVMS Guide to System Security: OpenVMS Version 8.4 > Appendix A Assigning Privileges
The SYSNAM privilege lets the user's process bypass discretionary access controls on the system logical name table in order to insert names into the system logical name table and delete names from that table by using the Create Logical Name ($CRELNM) and Delete Logical Name ($DELLNM) system services. A process with this privilege can use the DCL commands ASSIGN and DEFINE to add names to the system logical name table in user or executive mode and can use the DEASSIGN command in either mode to delete names from the table.
Grant this privilege only to the system operators or to system programmers who need to define system logical names (such as names for user devices, library directories, and the system directory). Note that a process with SYSNAM privilege could redefine such critical system logical names as SYS$SYSTEM and SYSUAF, thus gaining control of the system.