Existing Wording: For medication activities, the ActivityDefinition resource has some basic elements such as the product and quantity, but there is not enough information to describe more complex dosing scenarios. In those cases, the dynamicValue expression elements can be used to describe the values for elements that are present on the target resource, but not in the definitional resource

Comment:

Enable the same approach to be used for activities other than medications. E.g., for a ProcedureRequest, to specify bodySite.

Summary:

What about bodySite for ProcedureRequest, for example