Limit scope of #define labels

Question

What is the correct strategy to limit the scope of #define labels and avoid unwarranted token collision?

In the following configuration:

Answer 1

C is a structured programming language. It has its limitations. That is the very reason why object oriented systems came in 1st place. In C there seems to be no other way, then to understand what your header files's variables start with _VARIABLE notation, so that there are less chances of it getting over written.

in header file 
_ZERO 0

in regular file

ZERO 0