C51 FATAL-ERROR - ACTION: PARSING SOURCE-FILE ERROR: PREPROCESSOR: MACROS TOO NESTED C51 TERMINATED.
PLEASE TELL ME HOW TO SOLVE THIS ERROR.
It is a Keil proprietary keyword: http://www.keil.com/support/man/docs/c51/c51_le_memtypes.htm
Note that all the product manuals are available online: http://www.keil.com/support/man_c51.htm