Previously, the match_type element was a controlled vocabulary managed as a relatively static enum in LinkML. Given the many ways in which we may want to extend match_types, we now think it is better to define an external vocabulary for this.

This issue serves as a warning to that end: when the proposal is approved by the core team, elements like HumanCurated, Lexical etc will have to be prefixed like:

sssom:HumanCurated, sssom:Lexical.