XML Schema constraints applied to the NHS Health Checks Data Set.
| Data Element | XML Schema Format/Length | Allowed Values | Range | Pattern Match | Reason / Comment / XML Choice | 
| AGE AT ATTENDANCE DATE | n3 | None | None | None | Default Code 999 not applicable - removed | 
| ETHNIC CATEGORY | max an2 | None | None | None | Existing Format/Length means fixed length which is incorrect. Unable to change this as it is used in other data sets. Second character can be for local use. Format/Length amended to max an2. | 
| LOWER LAYER SUPER OUTPUT AREA (RESIDENCE) | an9 | None | None | None | Existing Format/Length annnnnnnn - schema format an9 | 
| ORGANISATION CODE (CODE OF COMMISSIONER) | min an3 max an12 | None | None | None | Field size extended to future proof for ODS ORGANISATION CODE changes | 
| ORGANISATION CODE (NHS HEALTH CHECK PROVIDER) | min an3 max an12 | None | None | None | Field size extended to future proof for ODS ORGANISATION SITE CODE changes | 
| SMOKING STATUS CODE | an1 | 1,2,3,4,Z | None | None | Default Code 9 not applicable - removed |