/sys$common/syshlp/helplib.hlb CC, /LIBRARY  *Conan The Librarian (sorry for the slow response - running on an old VAX)

  Indicates that the associated input file is a library containing
  source text modules specified in #include directives.  The compiler
  searches the specified library for all #include module names that
  are not enclosed in angle brackets or quotation marks.  The name of
  the library must be concatenated with the file specification using
  a plus sign.  For example:

  CC DATAB/LIBRARY+APPLIC