[JoBullet]

Today I learned that pattern name is called prefix. The prefix is the part of pattern that begins at the beginning of the pattern and ends on first occurrence of non-alphabetic character.
Note: in this context alphabetic means it is member of: 'a'..'z', 'A'..'Z', '0'..'9', '@', '_'.
This is important because warning 201("redefinition of constant/macro") is issued when there are more then one equivalent PREFIXes(NOT patterns).

Код:

#define pattern substitution
#define prefix<non-alphabetic substitution
#define prefix{non-alphabetic warning 201 issued

I have also learned that trailing argument in pattern is cut off if it exists because it could match anything,

Код:

#define _X%1 whatever

actually is equivalent to

Код:

#define _X whatever