Add a new specification called Foundation Types, containing the old Support IM assumed types, date/time types, along with some other basic types needed by the openEHR type system.
Interval of Duration seems to be missing - needed in prescribing - "Take 2 tabs every 4-6 hours"
It's there. See section 5 - this shows the Interval<T:Ordered> type; the 'T:Ordered' means that T can be any type inheriting from Ordered, which is an abstract type shown in section 3.
Now if you go to the Time types in section 6, you'll see that IDuration , Duration and Iso8601_duration all inherit from Ordered (see near top of diag).
You may be looking at the diagram in section 6.4 - it just shows how Interval<X> are generated for one time type, i.e. Date. The same diagram applies to the other date/time types. Do we need any extra wording - to me it is clear
thx - just me being dense