When GMP uses gcc style inline assembler in C files, like in gmp-impl.h, "__asm__" is used in most places, but some use just "asm". One reason for using __asm__ is that it makes it possible to compile the code with gcc -std=c89 (which is useful for finding accidental uses of Gnu C or c99 features). I don't know if there are any drawbacks to "__asm__". /Niels