diff --git a/registry/release-units/mas.yaml b/registry/release-units/mas.yaml
new file mode 100644
index 0000000..244ee98
--- /dev/null
+++ b/registry/release-units/mas.yaml
@@ -0,0 +1,45 @@
+# No owner classification file. Recorded confidential/medium for this
+# validation MX: it holds relay credentials and message evidence, and it is
+# capped rather than a production mail service.
+kind: release-unit
+unit_id: mas
+owner: mail-address-semantics
+contract_version: 1.0.0
+data_classification: confidential
+criticality: medium
+composition:
+  purpose: Covers the live MAS reference MX and statute service.
+  member_repos:
+  - repo: mail-address-semantics
+    role: rollout owner
+    deployables:
+    - mas-mx
+    - mas-statute
+rollout_contract:
+  default_mode: owner-deploy
+smoke_contract:
+  required:
+  - workload-ready
+rollback_contract:
+  order:
+  - owner-rollback
+workloads:
+- kind: Deployment
+  namespace: mas
+  name: mas-mx
+- kind: Deployment
+  namespace: mas
+  name: mas-statute
+pins:
+  component:
+    name: ocm.railiance.dev/mas
+    version: live
+  resources: []
+  sources:
+  - name: mail-address-semantics
+    type: git
+    version: live
+    digest:
+      hashAlgorithm: SHA-1
+      normalisationAlgorithm: gitCommit/v1
+      value: f4c4aaa4a66bfb43fe008a06eeb047968dcccafd