The unique source key of an inbox list item.
#include "bb/pim/unified/unified_data_source.h"
typedef char* uds_source_key_t;
BlackBerry 10.2.0
When you add an inbox item to the BlackBerry Hub using uds_item_added(), this item is assigned a unique source key. Typically, this key is unique per account and is used to represent the list item that was added.