iso6523Code

An organization identifier as defined in ISO 6523(-1). The identifier should be in the `XXXX:YYYYYY:ZZZ` or `XXXX:YYYYYY`format. Where `XXXX` is a 4 digit _ICD_ (International Code Designator), `YYYYYY` is an _OID_ (Organization Identifier) with all formatting characters (dots, dashes, spaces) removed with a maximal length of 35 characters, and `ZZZ` is an optional OPI (Organization Part Identifier) with a maximum length of 35 characters. The various components (ICD, OID, OPI) are joined with a colon character (ASCII `0x3a`). Note that many existing organization identifiers defined as attributes like leiCode (`0199`), duns (`0060`) or GLN (`0088`) can be expressed using ISO-6523. If possible, ISO-6523 codes should be preferred to populating vatID or taxID, as ISO identifiers are less ambiguous.