The input files expected by LIB depend on the mode in which it is being used, as shown in the following table.
| Mode | Input |
| Default (building or modifying a library) | COFF object (.OBJ) files, COFF libraries (.LIB), 32-bit Object Model Format (OMF) object (.OBJ) files |
| Extracting a member with /EXTRACT | COFF library (.LIB) |
| Building an export file and import library with /DEF | Module-definition (.DEF) file, COFF object (.OBJ) files, COFF libraries (.LIB), 32-bit OMF object (.OBJ) files |
Note OMF libraries created by the 16-bit version of LIB cannot be used as input to the 32-bit version of LIB.