I made a blog entry in March about Vietnam, where a postal code exists but without the populace knowing about it.

Two more examples caught my eye this week, in both cases where a country announced the introduction of a postal code system: Nigeria and Dominican Republic.

In both countries a postal code exists - in Nigeria's case since 2000 - and in both cases this information has been placed at one time or another on the national postal authority's website. It is very interesting that in all of the comments placed in reaction to these news items up to this point, only one persons suggested that they thought that a postal code system was already in place.

Regardless of the reasons why the existing postal code systems in either country had not been fully publicised before now, this is another indicator of how careful form designers need to be in their use of required fields. Nigeria may have a postal code system, but if nobody knows about it or uses it, requiring that field on a form will only lead to customer loss and data quality reduction.

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