Will add the following language to the unitOption and unitValueSet extensions: "If this extension present and an answer is provided for the question item in the QuestionnaireResponse, then the valueQuantity SHALL have a Quantity.code and Quantity.system that match the Coding.code and system of one of the allowed values if the Coding has a code and/or system.  If the Coding only has a display, then the Quantity.unit must match.  (Note that Coding with only a display is strongly discouraged.)  If there is a match on code and system, but no match on display/unit, systems MAY raise a warning.  However, because of translation and bandwidth considerations, some systems MAY opt to drop the unit or express it in an alternate language." For the unitValueSet, will also add: "Validation of the Quantity unit MAY be performed by using the $validateCode operation, populating the elements passed into the operation from the Quantity.code, system and unit elements."