file-spec

    If you enter a file specification with the /MAP qualifier, the
    linker creates an image map file with that file name. If you do
    not enter a file type after the file name, the linker assumes a
    file type of .MAP.

    If you do not enter a file specification with the /MAP qualifier,
    the linker creates an image map file with the file name of the
    first input file specified on the command line and the file type
    .MAP. (If there are no input files specified on the command line,
    the linker names the map file .MAP.)

    If you append the /MAP qualifier to one of the input file
    specifications, the linker creates an image map file with the
    file name of the file to which the qualifier is appended, using
    the .MAP file type.