/MA[[option]]
This option passes the specified option to the Microsoft Macro Assembler (MASM). The option must follow immediately after /MA, without an intervening space, slash (/), or hyphen (–).
For example, /MAZi passes the Zi option to MASM.
Files listed on the command line with the extension .ASM automatically cause MASM to be invoked. All MASM-supported options are accepted.