Coding list versions

[KitWallace]

I have been working on new versions of the codelists and realized that its more complicated than I thought

Code lists can be changed in several ways:

• changing the definition of a code -it name or definition
• add a new code - likely to be benign
• removing a code - this is more problematic:

The sector (purpose) list is typical example although it also applies to county codes where AN has been removed.

New documents need to be validated against the new version of the sector codelist with the deleted codes removed.

Existing documents may need to be validated and viewed against the codelist which was current when the document was created.

At the corpus level, the set of codes which appear in an interface has to be the union of these lists since the corpus contains documents covering all versions.

In my approach to updating the lists, I have been thinking about the needs of the database for a list so my updates are wrong.

Internally, the working codelist is currently copied from the last version of the codelist when the the codelists are cached. This has to be changed so that the working list is the union of codes in all versions.

This doesn't address the relationship between codelist versions and the IATI standards except that it indicates that even externally authorized codelists need to be versioned and that old versions of the codelists need to be available so that consumers of the data can understand older documents.

[KitWallace]

No progress on this so only the lastest versions are used - this will mean that some now obsolete codes will not be decoded - further attention will be needed