The Set Logical Name routine requests the calling process's
    command language interpreter (CLI) to define or redefine a
    supervisor-mode process logical name. It provides the same
    function as the DCL command DEFINE.

    Format

      LIB$SET_LOGICAL  logical-name [,value-string] [,table]

                       [,attributes] [,item-list]

      Either the item-list or value-string argument must be
      specified. If both item-list and value-string are specified,
      the value-string argument is ignored.