A number between zero and one less than the value returned by _RTC_NumErrors.
A value to assign to this errnum. For example, you might use _CRT_ERROR. If you are using _CrtDbgReport as your error handler, ErrType can only be one of the symbols defined in _CrtSetReportMode. If you have your own error handler (_RTC_SetErrorFunc), you can have as many ErrTypes as there are errnums.
An ErrType of _RTC_ERRTYPE_IGNORE has special meaning to _CrtSetReportMode; the error is ignored.