In the batch section: http://hl7.org/fhir/2018May/http.html#3.1.0.17.1

It states: Static references within a Bundle.entry.resource to another Bundle.entry.resource that is being created within the batch are considered to be non-conformant.

We do not define what a static reference is, nor reference it elsewhere in the spec. I believe this is intended to just say that no references of any kind are allowed to resources being created in the batch. If so, we can remove the "static" qualifier.

If it's intended to mean some form of reference specifically, we need to define that on our reference definitions (and link to it)