Stages from data source to databank. Data providers split their datasets at source into two parts: demographic data (File_1) and clinical data (File_2). File_1 is transferred to Health Solutions Wales for anonymisation and assignment of the Anonymous Linking Field (ALF). This is transferred to HIRU as File_3. File_2 is transferred directly from the data provider to HIRU. A join-key assigned by the data provider allows File_2 and File_3 to be joined at HIRU to build the SAIL databank.