The “implementation_key” Declaration Specifier

Syntax

Within a __declspec, this specifier is

 implementation_key ( number )

It is an error (C2330) to apply the implementation_key attribute except inside a map region, as opened and closed by #pragma start_map_region and #pragma stop_map_region.

It is a syntax error (C2059) if the first token after implementation_key is not an opening parenthesis or the next token is not a constant (for number). Only the low 32 bits of number are significant. It is a syntax error (C2059) if the token after number is not a closing parenthesis.