The LIB= directive is optional and has the following properties.

      1. The time and date stamps of all files placed in the LIB=
         directives will be compared to the time and date stamp of the
         target file.

      2. If the target is older than any file in the LIB= directive
         it (the target) will be relinked.

      Any file referenced in a LIB= directive that does not exist as an
      actual file will stop the make process with an appropriate error.