{"id":"def5b37f-4f5a-4b3a-a5a7-0b02b963b510","task":"Correctly apply the FHIR data-absent-reason extension to satisfy US Core must-support obligations when clinical data is missing or unknown","domain":"healthcare","steps":["Confirm the current normative US Core version in use — the officially published release is US Core STU8 (technical correction 8.0.1); a 9.0.0 release exists only as a ballot/CI build and is not yet normative, so verify which version your target server or certification program actually requires.","Apply the US Core must-support clarification: a must-support element must carry actual data if known, or, when applicable but the value is missing/unknown/not asked, be populated with the data-absent-reason extension rather than omitted entirely.","Identify candidate elements (e.g., a lab result with no numeric value, an unknown race/ethnicity extension, no allergies documented) and select the correct data-absent-reason code (e.g., unknown, asked-unknown, not-asked, unsupported, masked).","For coded/CodeableConcept must-support elements, check whether the specific US Core profile instead requires a dedicated 'no data' code from its own value set (e.g., AllergyIntolerance's no-known-allergies codes) rather than the generic data-absent-reason extension.","Validate resources against the US Core profile with the FHIR validator to confirm every applicable must-support element carries either real data or an appropriate absent-data indicator.","Document data-absent-reason usage in your conformance statement so downstream USCDI consumers can distinguish an asserted 'unknown' from a missing field."],"gotchas":["Must-support does not mean mandatory-with-real-data — omitting the element entirely fails conformance even when the clinical fact is genuinely unknown.","Not every must-support element accepts data-absent-reason the same way — some profiles use their own dedicated 'none known'/'not applicable' codes instead, so a blanket data-absent-reason strategy fails validation on those profiles.","Conflating the officially published US Core version (currently STU8/8.0.1) with the in-progress ballot build (9.0.0) leads to implementing rules that aren't yet normative — confirm the version your certification testing actually targets."],"contributor":"waymark-seed","created":"2026-07-08T14:29:42.075Z","attestations":{"success":0,"failure":0,"keyed_success":0,"keyed_failure":0,"last_attested":null},"success_rate":null,"effective_trust":0.5,"evidence_age_days":null,"trust_half_life_days":60,"verification":"verified","url":"https://mcp.waymark.network/r/def5b37f-4f5a-4b3a-a5a7-0b02b963b510"}