diff --git a/api/v1/swagger.json b/api/v1/swagger.json
index 362780ad79..249e71ba7e 100644
--- a/api/v1/swagger.json
+++ b/api/v1/swagger.json
@@ -21,5 +21,8 @@
   },
   "parameters": {
     "$ref": "parameters.json"
+  },
+  "x-primitives": {
+    "$ref": "x-primitives.json"
   }
 }
diff --git a/api/v1/x-primitives.json b/api/v1/x-primitives.json
new file mode 100644
index 0000000000..ae8750e0cb
--- /dev/null
+++ b/api/v1/x-primitives.json
@@ -0,0 +1,41 @@
+{
+  "biblionumber": {
+    "type": "string",
+    "description": "internally assigned biblio identifier"
+  },
+  "borrowernumber": {
+    "type": "string",
+    "description": "internally assigned user identifier"
+  },
+  "branchcode": {
+    "type": ["string", "null"],
+    "description": "code of patron's home branch"
+  },
+  "cardnumber": {
+    "type": ["string", "null"],
+    "description": "library assigned user identifier"
+  },
+  "email": {
+    "type": ["string", "null"],
+    "description": "primary email address for patron's primary address"
+  },
+  "firstname": {
+    "type": ["string", "null"],
+    "description": "patron's first name"
+  },
+  "itemnumber": {
+    "type": ["string", "null"],
+    "description": "internally assigned item identifier"
+  },
+  "phone": {
+    "type": ["string", "null"],
+    "description": "primary phone number for patron's primary address"
+  },
+  "reserve_id": {
+    "description": "Internal hold identifier"
+  },
+  "surname": {
+    "type": "string",
+    "description": "patron's last name"
+  }
+}