The ProductShelfLife, which is shared by PackagedProductDefinition and DeviceDefinition has some issues.

1 - it has an identifier. This is a legacy issue because it was originally a resource, when first drafted, before being turned into a datatype. Resources have to have identifier, but that was the only reason for it. That should be removed.

2 - mandatory "period". This is for e.g. "2 years". However in many cases the shelf life is found as text e.g. "use for a maximum of 2 years after opening". So this period should be period[x] Quantity|string 1..1. A value is always needed. Update 6th April call - friendly amendent - this can also be optional, sometimes you only need the specialPrecautionsForStorage

3 - mandatory "type". This is to say "shelf life after opening" or "shelf life after mixing". But this concept is not always known (at least as separate data), so it should be possible to miss this out and have the whole thing in ProductShelfLife.periodString

This resource is shown as being owned by Pharmacy and Maturity Level 3, but I believe that both of those are errors. It was created by BR&R and is not connected to any Pharmacy models and is definitely not maturity level 3 (probably zero).