The view descriptor flags are read from the view message by reading the PR_VD_FLAGS property. Currently, there is only one flag which defines the sort order of the messages in the folder. The sort order is applied to the messages after they are grouped (optional). Each group of messages will be grouped in ascending or descending order based on this flag. The flag VDF_SORTDESCENDING should be set for descending order or cleared for ascending order. The sort order of the grouped columns is defined separately in ulCatSort. All other bits are reserved and must be cleared.