/MODEL (Alpha only)
       /MODEL={ANSI | ARM}
       /MODEL=ARM (D)

    On Alpha systems, determines the layout of C++ classes, name
    mangling, and exception handling.

    On I64 systems, the default (and only) object model & demangling
    scheme used is the I64 Application Binary Interface (ABI). The
    compiler accepts the /MODEL qualifier, but it has no effect.

    On Alpha systems, /MODEL=ARM is the default and generates objects
    that are link compatible with all releases prior to HP C++
    version 6.3, and with all objects compiled with the /MODEL=ARM
    qualifier in releases of HP C++ Version 6.3 or later. Specifying
    this option defines the macro __MODEL_ARM.

    The /MODEL=ANSI qualifier supports the complete ISO/ANSI C++
    specification, including distinct name mangling for templates.
    The ANSI model also reduces the size of C++ non-POD class
    objects. Note that this option generates objects that are not
    compatible with all prior and future releases of HP C++, or with
    objects compiled using the /MODEL=ARM qualifier.

    If you specify the /MODEL=ANSI qualifier, you must recompile
    and relink (using CXXLINK/MODEL=ANSI) your entire application,
    including libraries. Specifying this option defines the macro
    __MODEL_ANSI.