Use this macro in a request handler DLL to mark the start of a handler map.
This macro has no functional use; it is merely supplied as a notational convenience.
The handler map is used to map the names of request handlers (as specified in server response files) to the C++ classes that implement those handlers.
A handler map is marked by the BEGIN_HANDLER_MAP and END_HANDLER_MAP macros.
Entries in the map can be provided by any of the following macros: