So a flag that recently turned up in validation is that “NA” is a categorical missingness values in the parts list, and “NA” is also Namibia’s ISO code in the zones and countries reference tables.
This, in theory, shouldn’t lead to a collision because the countries field in addresses should only be populated by values in the countries reference table. However, there are a number of fields in which we’ve allowed entries with a missingness part type to also populate these fields. I will try to go through and make some structural considerations so that “NA” the missingness indicator cannot be used in the country field, (opting instead for “NULL”, nr, etc.) to avoid possible confusion and data mistakes moving forward.