Uniqueness

A record’s identifying fields must be unique amongst all other current records of the same record type.

Deleted records are not considered; if a record is given a DELETE modification then its identifying fields may be reused. Note that once a record exists it isn’t possible to UPDATE its identifying fields.

This rule ensures that the correct record to modify can be unambiguously identified when changes to a record are communicated, because records being updated in the transaction stream are identified by their identifying fields.

Examples

An additional code has type A, code 123 and start date 2021-01-01. If another additional code is created with type A, code 123 and start date 2021-01-01, then the creation will fail this rule.

If another additional code is created with a different start date (e.g. created with type A, code 123 and start date 2021-01-02) then it will not fail this rule (although it may fail another rule about overlapping dates.)

If the first original code is deleted, then creating a new additional code with type A, code 123 and start date 2021-01-01 will then not fail the rule.