The Embedded Warrior Library for C conforms to the library described in the ISO/IEC9899:1999 ( "C99" ) standard. The EWL also conforms to the previous standard, ISO/IEC9899-1990 ( "C90" ). EWL uses a macro, EWL_ C99, to separate C90 features from C99features. If EWL_ C99 is defined to have the value 0 before building the EWL C library, only those parts of the library that were defined in C90 are compiled, yielding a smaller library. If EWL_ C99 is defined to have a non-zero value before building the library, the full EWL C library is compiled to conform to C99.