I was just pointing out that these are extensions to ANSI and therefore not standard.
You're right; any compiler targetted at any specific embedded target will have its own extensions.

My point was that these are not standard; you can't assume that the way Keil does it will necessarily be like the way any other compiler does it.

You're right; if you want to make it portable, you need to "encapsulate" all the implementation-specifics in some way.
I have similar preprocessor directives to yours to enable me to build & run my code in a Borland C++ Builder Project.


Actually, Keil's xdata, pdata etc aren't macros; the are C51 keywords which Keil have added as extensions to the ANSI 'C' language (perhaps you're thinking of XBYTE, etc?)