We are unable to tag the datetime choice with the add'l USCDI extension.  The technical issue with the add'l USCDI extension is that its context is on the element and not the type choice.  We document the requirement in the Profile specific implementation Guidance: Notes for  Date of Death ,  Previous Name ,  Suffix ,  Previous address , and  Preferred Language  USCDI Data Elements: Date of Death is communicated using the  Patient.deceasedDateTime  element. Decision:  Update the guidance to indicate that certifying systems shall support the Patient.deceasedDateTime  element   Date of Death is communicated using the  Patient.deceasedDateTime element.   Although Patient.deceased [x] is marked as 𝗔𝗗𝗗𝗜𝗧𝗜𝗢𝗡𝗔𝗟 𝗨𝗦𝗖𝗗𝗜, the certifying system is not required to support both, but SHALL support at least Patient.deceasedDateTime   Decision: tag this as a 6.1.0 patch