Why Would You Ever Change a Code Value?

Sometimes we see updates to reference data where a code is actually changed.  Why would you do this if the description remains unchanged, or even if the description changes?

There are actually several reasons.  My first experience of this was political, when I was working at the United Nations.  One country did not like its alpha-3 country code as it considered it insulting and required that it be changed.  In several other cases, the country changed in some profound way and the government renamed the country, and also demanded that the alpha-3 country code be changed to reflect the new reality.

A more common requirement is that the underlying semantics of something has changed, even if the descriptive name remains the same.  For instance, it might be that the industrial sector “Horse Trading” is suddenly extended to include “Mule Trading”, but it retains the name “Horse Trading”.  It makes sense to change the code as the sector is now much broader than it was and historical reporting with the former “Horse Trading” will show a sudden and otherwise inexplicable discontinuity.

Changing a code value, therefore, can be justified.  What is very difficult, however, is changing a code value retrospectively, which was required with the examples from the UN mentioned above.  That is a subject for another day.