Will add a comment in the core spec that says: "This element covers a broad range of relationships, from "somewhat inspired by" to "fully compliant with".  The work group expects to define a standard extension that allows clearer differentiation between the specifics of the derivation relationship where this is needed - e.g. to determine substitutability and validation expectations."   We will submit a new change request to define an extension called derivationType with type CodeableConcept with the definition: "Provides more precision about the type of derivation relationship that exists" Will define an extensible binding with three codes: { } extends "extends" Indicates this Questionnaire includes all of the items and permitted answers present in the target Questionnaire, however it also adds additional items and/or answers, such that a QuestionnaireResponse against the referencing Questionnaire may no longer be valid against the referenced Questionnaire. compliesWith "complies with" Indicates this Questionnaire is derived in a manner that ensures that QuestionnaireResponses completed against this form will also be valid against the referenced questionnaire.  To be a valid constraint, linkId, item types, and item order must align and all required items and answers must be included. However, cardinality can be tightened and answers can be restricted. If a Questionnaire complies with a parent Questionnaire, that does not mean that the derived Questionnaire is considered to have the same validity as the parent Questionnaire. inspiredBy "inspired by" Indicates that some portion of the content of this Questionnaire was drawn from the referenced Questionnaire.  Responses created against this Questionnaire have no expectation of being valid against the referenced Questionnaire. linkIds, question text, answer choices, etc. may all vary and items may have been added or removed.