Macro Precedence Rules

When the same macro is defined in more than one place, the definition with the highest priority is used:

• Highest) Command line

• Description file

• TOOLS.INI file

• Environment variables

• Lowest) Predefined macros (such as CC and AS)

If you invoke NMAKE with the Overriding Macro Definitions (/E) option, macros defined by environment variables take precedence over those defined in a description file.