C.2.4 Specification Libraries

  LIB-DEFN        ::= library LIB-NAME LIB-ITEM...LIB-ITEM
  LIB-ITEM        ::= SPEC-DEFN  |  VIEW-DEFN
                    | ARCH-SPEC-DEFN  |  UNIT-SPEC-DEFN
                    | from LIB-NAME 
                         get ITEM-NAME-OR-MAP ,..., ITEM-NAME-OR-MAP end/

  ITEM-NAME-OR-MAP::= ITEM-NAME  |  ITEM-NAME "|->" ITEM-NAME
  ITEM-NAME       ::= SIMPLE-ID

  LIB-NAME        ::= LIB-ID | LIB-ID VERSION
! LIB-ID          ::= URL  |  PATH
  VERSION         ::= version NUMBER "."..."." NUMBER