nothing is sure but compilers for embedded systems often include it

anyway the sequence

#define true 0==0
#define false 0==1
typedef unsigned char byte;
typedef unsigned int__8 (or 16 or 32 or 64) WORD;
typedef unsigned int__16 DWORD;

could be useful and just clarify the code

i love the
typedef register unsigned char whatyouwant (for 8 bit use)
i believe not many compiler accept it