VMS Help NCS Command, Command Qualifiers, /LIBRARY  *Conan The Librarian (sorry for the slow response - running on an old VAX)

  /LIBRARY[=file-spec]

   By default, NCS assumes  all  library  operations  are  directed  at
   SYS$LIBRARY:NCS$LIBRARY.NLB; that is, NCS assumes  a  default  file
   type of NLB and a default directory of  SYS$LIBRARY.  However,  you
   can use the /LIBRARY qualifier to override  the  default  when  you
   want to work in a different NCS library.