File Types

The MS-DOS programming tools can create and process many different file types. The following extensions are used by convention for these files:

Extension File type

.ASM Assembly-language source file

.C C source file

.COM MS-DOS executable load module that does not require relocation

at runtime

.CRF Cross-reference information file produced by the assembler for

processing by CREF.EXE

.DEF Module-definition file describing a program's segment behavior

(MS OS/2 and Microsoft Windows programs only; not relevant to

normal MS-DOS applications)

.EXE MS-DOS executable load module that requires relocation at

runtime

.H C header file containing C source code for constants, macros,

and functions; merged into another C program with the #include

directive

.INC Include file for assembly-language programs, typically

containing macros and/or equates for systemwide values such as

error codes

.LIB Object-module library file made up of one or more .OBJ files;

indexed and manipulated by LIB.EXE

.LST Program listing, produced by the assembler, that includes

memory locations, machine code, the original program text, and

error messages

.MAP Listing of symbols and their locations within a load module;

produced by the linker

.OBJ Relocatable-object-code file produced by an assembler or

compiler

.REF Cross-reference listing produced by CREF.EXE from the

information in a .CRF file