The specification is not clear about the expected behavior of differential elements and how they contribute to the generation of their corresponding snapshot elements.

For example, several properties in ElementDefinition are multi-cardinality (i.e., arrays), but there is not a consistent approach to how these arrays are applied to the original element definition (or a slice base) to produce an updated snapshot element. The entire original array might be replaced by the array in the differential (e.g., `type`), or the differential array might be appended to the original array (e.g., maybe `mapping`?), or there might be a more complex "upsert" type operation (e.g., `constraint`).  We need to clarify which properties use which behaviors.

For those "upserts" (or "matched updates") we also need to define if the updates are "sparse" or "complete".

It is also worth considering if the behavior differs when slices "inherit" properties from their base.

See: https://chat.fhir.org/#narrow/stream/215610-shorthand/topic/Exclude.20inherited.20array.20elements/near/228613574