implementing Realms as an MMT structural feature
We have this global language feature of realms, see http://kwarc.info/kohlhase/papers/cicm14-realms.pdf and http://kwarc.info/kohlhase/papers/cicm15-induced.pdf and http://kwarc.info/kohlhase/papers/cicm15-recaps.pdf This is a very well-understood practical device that makes theory graphs much closer to mathematical practice.
This needs to be implemented in MMT (following and building on Mihnea Iancu's thesis), and a management interface needs to be designed. And of course tested on the examples Mihnea and I have designed.