6.2 COFF Output Format

The COFF object module format is suitable for flat, non-segmented memory models. In most cases the COFF format is used for 32-bit code. However, it's possible to create a 64-bit COFF module if the current cpu is .x64 when the .MODEL directive is parsed ( note that -win64 is the usual way to create modules for 64-bit Windows ). To some extent 16-bit code is also supported with COFF, although OMF will always be the better choice then.