MACRO            Initiate macro definition                          Directive

  MACRO name [dummy_arg [,dummy_arg]...]        ; Ideal mode
  macro_body
  ENDM

  name MACRO [dummy_arg [,dummy_arg]...]        ; MASM mode
  macro_body
  ENDM

    Defines a multiline macro to be expanded later when name is encountered.

    Macros may be nested to any depth, may call other macros, and may call
    themselves. They may also be redefined.

    Macros generate code when they are called, not when defined. All
    addresses generated are relative to the position of where the macro is
    called, not where it is defined.

    dummy_arg is a symbolic name used as a place holder for the actual
    argument passed to the macro when it's invoked; it has the following
    syntax:
                dummy_name [:dummy_type]

    The optional dummy_type specifies something about the form the actual
    argument must take when you invoke the macro. The following types are
    supported:

        dummy_type      Meaning
        REQ             Argument cannot be null or spaces.
        =<text_string>  Bracketed text string is the default value for the
                        dummy argument when the actual argument is null or
                        contains spaces.
        VARARG          Actual argument consists of the rest of the macro
                        invocation, interpreted as a list of arguments.
                        Commas and angle brackets are added to ensure this
                        interpretation.
        REST            Actual argument consists of the rest of the macro
                        invocation, interpreted as raw text.


    Invoking a multiline macro

    The syntax for invoking a general multiline macro is this:

        macro_name [argument [[,]argument]...]

    Each argument (separated by commas or spaces) represents a text
    string. You can specify this text string in the following ways:

    ■ as a contiguous group of characters, not containing any whitespace,
      commas, or semicolons
    ■ as a group of characters delineated by angle brackets (< >), which
      can contain whitespace, commas, and semicolons
    ■ as a single character preceded by a ! character (which is equivalent
      to enclosing the character in angle brackets)
    ■ as an expression preceded by a % character, which represents the
      text value of the expression appropriate for the currently selected
      radix