Healthcare Provider Identifiers (HPI-I and HPI-O)
Format checks for 16-digit provider and organisation identifiers.
HPI-I identifies an individual provider and starts with 800361; HPI-O identifies an organisation
and starts with 800362. Both are 16 digits with a Luhn check digit, like the IHI. The parser
recognises them in XCN-shaped provider fields (PV1-7/8/9/17, ORC-12, OBR-16, PRD-7) and in HD-shaped sending and
receiving facility fields.
Synthetic examples: HPI-I 8003613771441698, HPI-O 8003626106024393.