Prepare 0.3.0: ICD-11 MMS integration

input/fsh/extensions/icd11ClusterExpression.fsh

@@ -0,0 +1,68 @@
+// ============================================================
+// icd11ClusterExpression.fsh
+// Extension for ICD-11 postcoordinated cluster expressions
+// Context: Coding (broad — usable across all ICD-11 coded elements)
+// ============================================================
+
+Extension: ICD11ClusterExpression
+Id: icd11-cluster-expression
+Title: "ICD-11 Cluster Expression"
+Description: """
+Carries a postcoordinated ICD-11 cluster expression as a single string
+on a Coding element where the stem code alone is insufficient to fully
+represent the clinical concept.
+
+A cluster expression combines a stem code with one or more satellite
+codes using the & operator (combination) or / operator (specificity).
+Example: NC72.Z&XK8G&XJ7ZH&XJ7YM
+  - NC72.Z  — stem: Fracture of femur, unspecified
+  - XK8G    — satellite: laterality
+  - XJ7ZH   — satellite: fracture subtype
+  - XJ7YM   — satellite: fracture open or closed
+
+Usage rules:
+  - SHALL only be present when the expression contains at least one
+    satellite code joined by & or / operators.
+  - Single stem codes SHALL be represented in Coding.code only and
+    validated via OCL $validate-code. The cluster validator at
+    https://icd11.dghs.gov.bd/cluster/validate explicitly rejects
+    stem-only expressions.
+  - The stem code in Coding.code SHALL match the leading stem code
+    in this expression string.
+  - Satellite codes in the cluster expression are exempt from the
+    Diagnosis/Finding class restriction that applies to stem codes
+    in Condition.code.
+  - Cluster expressions SHALL be validated against the Bangladesh
+    ICD-11 Cluster Validator at https://icd11.dghs.gov.bd/cluster/validate
+    prior to submission to the HIE.
+
+Cluster validator endpoint:
+  POST https://icd11.dghs.gov.bd/cluster/validate
+  Body: { "expression": "NC72.Z&XK8G&XJ7ZH&XJ7YM" }
+
+This extension is not MustSupport and is not mandatory. It is present
+only when postcoordination is clinically required. Cluster expressions
+are typically sourced from the WHO Electronic Coding Tool (ECT) at the
+point of care.
+"""
+
+* ^url = "https://fhir.dghs.gov.bd/core/StructureDefinition/icd11-cluster-expression"
+* ^status = #active
+* ^experimental = false
+* ^publisher = "Directorate General of Health Services (DGHS), MoHFW, Bangladesh"
+* ^contact.name = "DGHS Health Informatics Unit"
+* ^contact.telecom.system = #url
+* ^contact.telecom.value = "https://dghs.gov.bd"
+* ^jurisdiction = urn:iso:std:iso:3166#BD "Bangladesh"
+* ^context[+].type = #element
+* ^context[=].expression = "Coding"
+
+* value[x] only string
+* valueString 1..1
+* valueString ^short = "ICD-11 postcoordinated cluster expression string"
+* valueString ^definition = """
+The full postcoordinated cluster expression, including the stem code and
+all satellite codes joined by & or / operators. Example:
+NC72.Z&XK8G&XJ7ZH&XJ7YM. The stem code in this string SHALL match
+Coding.code on the parent Coding element.
+"""