MASM version 6.0 now includes ML.EXE, which replaces MASM.EXE. The ML.EXE utility both assembles and links, making the assembler's behavior identical to that of Microsoft compilers (such as CL.EXE for C and FL.EXE for FORTRAN). You can still assemble without linking by adding the /c option to the ML.EXE command line.
To simplify the transition from previous versions of MASM to MASM version 6.0, Microsoft has provided a special MASM.EXE utility. The new MASM.EXE is not an assembler. It simply translates the old-style command line into the new format and passes the command to ML.EXE.
Since MASM.EXE also sets certain options, you may want to look at Appendix A in the Programmer's Guide, “Differences between MASM 6.0 and 5.1,” before using MASM.EXE. This appendix lists all the new and changed features in MASM 6.0 and gives recommendations for updating existing code.