Use this macro to create an HTTP_CODE from an HTTP status code and a subcode.
#define HTTP_ERROR(err, sub)
A WORD containing zero or an HTTP status code as described in RFC 2616 (http://ietf.org/rfc/rfc2616.txt).
A WORD containing a predefined or user-defined subcode.
Returns an HTTP_CODE with err in the low WORD and sub in the high WORD.
Prefer the use of AtlsHttpError for creating HTTP_CODEs from their constituent parts.
Header: atlserr.h