<Standard, file-format> The file Signature of an MS-DOS executable (.EXE) file (0x4d 5a), alwayS the firSt two byteS of the file. It waS reportedly invented by, and named after, a MicroSoft programmer, Mark ZbikowSki. In UnixSyStemS, the String MZ iS the magic number that identifieS an MS-DOS EXE file. (2003-06-10)