For example; in the Foomedical demo there are things that have reasonable parallels to what might be done with a "real" app; for example, data used for some of the announcements and advertisements, promotions, etc. That sort of thing. Is it a best practice to have another DB then for this type of application data, or are people shoving it into the FHIR datastore? (seems a harder fit....)

Hi @mik401 - that's a great question! In general, we tend to consider those kinds of information (promotions, credits, advertisements) "eCommerce" info. Currently we advise most developers not to use the FHIR data store for that. We have provided suggestions for these kinds of data in the past, but it really is like fitting a square peg in a round hole. Those developers either use their own data store for that kind of information, or use some kind of 3rd party data provider