This option tells LIB to build an import library and an export file.



The optional filename argument consists of everything after the colon. It is valid for /def to have a colon but no argument to follow.


The /def option puts LIB into the mode in which it builds an import library and an export file. The optional filename argument names a module definition file that supplies directions.

A module definition file named in a /def option counts as an input file for the purpose of test-case reproduction.

Naming a module definition file has a side-effect, even if the file does not exist. The default name for the output file (i.e., import library, as might yet be named in a /out option) becomes the filename but with the file extension changed to “.lib”.