Module:Language/name/data/doc

This pulls data from data modules and bunches them together. Language names are gathered in this order:
 * 1) Module:Language/data/ISO 639-3 – as defined in ISO 639-3
 * 2) Module:Language/data/iana languages – as defined by the IETF-sanctioned IANA registry; names almost always the same as ISO, but does not include 3-letter codes for languages with 2-letter codes, hence the fallback
 * 3) Module:Language/data/wp languages – specific to Wikipedia; languages for which we've decided another name is better

In other words, a name set in wp languages will take precedence over one set in iana languages and that too would take precedence over one from iso 639-3. wp languages can be discarded by passing  to the parent module.