VMS Help SET, RIGHTS_LIST, Parameter  *Conan The Librarian (sorry for the slow response - running on an old VAX)

 id-name[,...]

    Specifies identifiers to be added to or removed from the process
    or system rights list. The id-name parameter is a string of 1 to
    31 alphanumeric characters, underscores (_),  and dollar signs
    ($);  each name must contain at least one nonnumeric character.