This language:

"If the element has a questionnaire-itemExtractionContext that corresponds to an existing resource or set of resources, then the intention is that the extracted content will replace those existing resources. (Typically in this situation, the same expression would have appeared on the same element as a questionnaire-itemPopulationContext expression. On the other hand if the itemExtractionContext simply refers to a resource type, then the intention is to create new instances."

is unclear.  Need to make clear that in the first case, we'd have a valueExpression that's a query, while in the second, there'd be a valueCode.  Also need to explain how to handle situations where it's "update if it exists, create otherwise".  (Finally, close the bracket.)

Suggest changing to:

"If the element has a questionnaire-itemExtractionContext with an fhir-xQuery valueExpression that corresponds to an existing resource or set of resources, then the intention is that the extracted content will replace those existing resources. (Typically in this situation, the same expression would have appeared on the same element as a questionnaire-itemPopulationContext expression.) On the other hand if the itemExtractionContext is a valueCode that refers to a resource type, then the intention is to create new instances of that resource type.  If there are multiple extraction contexts, the intention is that the 'code' extractions (i.e. 'create new') only occurs if none of the 'query' extraction contexts find resources of that type."