Specification allows two-letter country codes (following ISO 3166, part 1, alpha-2), but a solution should be available for country names which have been deleted from the ISO 3166-1 (for example Netherlands Antilles: AN). A solution might be to allow ISO 3166-3 (for example Netherlands Antilles: ANHH), however this does not solve the problem for disappeared country names that never had a ISO code. This is probably relevant for genebanks with old material in their collection.