The default implementation of several DgnElementSetTool methods calls OutputErrorMessage with these enum values to output errors, for example:
bool DgnElementSetTool::_OnInstall () { if (SOURCE_Fence == _GetElemSource () && !FenceManager::GetManager().IsFenceActive ()) { OutputErrorMessage (ERROR_NUM_NoFence); return false; } if (SOURCE_SelectionSet == _GetElemSource () && !SelectionSetManager::GetManager().IsActive ()) { OutputErrorMessage (ERROR_NUM_NoSSElems); return false; } // Don't allow install if destination model is unspecified... return (INVALID_MODELREF != _GetDestinationModelRef ()); }
A sub-class of DgnElementSetTool might also want to call OutputErrorMessage to output the default error message from a method it overrides. There is no significance to the actual enum values *anymore*.
HTH
-B