NOTE: Multiple repetitions of this extension are possible. All can be used when populating a Questionnaire item. However, when extracting from a QuestionnaireResponse, if more than one is specified then exactly one repetition must have the questionnaire-observationExtract extension present with a value of 'true'.

When there are multiple codes appropriate for extract (e.g. multiple possible observation codes for weight, reflecting measurement techniciques, whether the subject is fully clothed, etc.), the one selected for extraction should most accurately reflect the semantics of the question. For example, if the question is "Current body weight:", then it would be most appropriate to select a generic code that corresponds to the generic concept of "Body Weight" than it does to one that says "Body Weight - clothed", "Body Weight - measured", or "Body Weight - reported" as there is nothing about the question that indicates that any of those narrower meanings apply.

Additional details on the use of this extension can be found on the Questionnaire Population page.