Several of our recent projects have involved setting up languages that feel like 'child' languages of other languages, for a variety of reasons. Sometimes it's for marketing, so that content can be overridden for markets using a specific currency, other times it's to target a specific audience. Our classic examples are 'Euro English' and 'British English' - in either case, these are special cases of regular English. A more traditional example would be Canadian French - where most content would be the same as French, but some pages would want different spellings or customisations. We came across Amazee Labs' work on language fallback which inspired us to work on the Language Hierarchy project.