is "for legacy reasons". This actually makes little sense any more, and is problematic in that it assumes all ids have a numeric part. That assumption will likely break in the near future when we add Commons support. It'd much rather have the json contain simply string "Q1" than an array with the above elements. The reason why this has not happened yet is that it is a big breaking change to users of our API. Due to Commons it looks like we will soon be forced to make such a change though. (Such a change will be announced well in advance of being deployed of course.)