Module primvec 

The value array of a repeating FHIR primitive (audit F-86). The value array of a repeating FHIR primitive (audit F-86).

FHIR JSON represents a repeating primitive as parallel arrays: the value array, and an _element array carrying each position’s id/extension. A position that carries only an extension is a null in the value array:

{ "event": [null], "_event": [{ "extension": [ … ] }] }

That is valid FHIR — HL7’s own R4B examples use it — and Vec<T> cannot hold it: there is no way to represent “no value at this position”. Until 2026-08-10 the model rejected the null outright (and, before F-87’s fix the same day, then silently dropped the surrounding element). PrimVec is the value array as the wire defines it: a sequence of positions, each a value or an extension-only placeholder.

Structs

PrimVec

The values of a repeating FHIR primitive element (0..*).