The full command-line option is /[NO]OBJECT[=file-spec].

    Controls whether an object file is created and optionally
    provides a file specification. Do not use wildcard characters
    in this file specification.

    If you do not specify a file specification, the assembler creates
    an object file using the same name as the source file. For
    example, if you use a source file named XXX.M64, the assembler
    creates an object file named XXX.OBJ.

    The default qualifier is /OBJECT.