Medicare provider number check character

How the eight-character provider number is validated.

A Medicare provider number identifies a practitioner at a specific practice location. It has a six-digit stem, a practice location character and a check character, for example 2426621B.

The algorithm

1. Multiply the six stem digits by 3, 5, 8, 4, 2, 1 and sum.
2. Map the location character to a value (0–9 then A–Y skipping I and O: A=10 … Y=32) and add six times that value.
3. Take the sum modulo 11 and index into YXWTLKJHFBA to get the check character.

The parser runs this when an XCN or PLN field is typed AUSHICPR, or when a value has the exact 8-character shape. Untyped matches are warnings rather than errors because an 8-character MRN can look the same.

See it fire on a mangled sample