diff --git a/generate-reader.uc b/generate-reader.uc
index c971827..f2fca18 100755
--- a/generate-reader.uc
+++ b/generate-reader.uc
@@ -74,6 +74,12 @@ let GeneratorProto = {
 				'return match(value, /^[0-9a-f][0-9a-f]:[0-9a-f][0-9a-f]:[0-9a-f][0-9a-f]:[0-9a-f][0-9a-f]:[0-9a-f][0-9a-f]:[0-9a-f][0-9a-f]$/i);'
 			]
 		},
+		"uc-mobility": {
+                        desc: 'Mobility Domain',
+                        code: [
+                                'return match(value, /^[0-9a-f][0-9a-f][0-9a-f][0-9a-f]$/i);'
+                        ]
+                },
 		"uc-host": {
 			desc: 'hostname or IP address',
 			code: [
diff --git a/schema/interface.ssid.roaming.yml b/schema/interface.ssid.roaming.yml
index f274720..53eae15 100644
--- a/schema/interface.ssid.roaming.yml
+++ b/schema/interface.ssid.roaming.yml
@@ -21,8 +21,7 @@ properties:
     description:
       Mobility Domain identifier (dot11FTMobilityDomainID, MDID).
     type: string
-    maxLength: 4
-    minLength: 4
+    format: uc-mobility
     examples:
     - abcd
   pmk-r0-key-holder:
diff --git a/schemareader.uc b/schemareader.uc
index 9b481c8..c325cc0 100644
--- a/schemareader.uc
+++ b/schemareader.uc
@@ -22,6 +22,10 @@ function matchUcMac(value) {
 	return match(value, /^[0-9a-f][0-9a-f]:[0-9a-f][0-9a-f]:[0-9a-f][0-9a-f]:[0-9a-f][0-9a-f]:[0-9a-f][0-9a-f]:[0-9a-f][0-9a-f]$/i);
 }
 
+function matchUcMobility(value) {
+	return match(value, /^[0-9a-f][0-9a-f][0-9a-f][0-9a-f]$/i);
+}
+
 function matchUcHost(value) {
 	if (length(iptoarr(value)) != 0) return true;
 	if (length(value) > 255) return false;
@@ -2812,11 +2816,8 @@ function instantiateInterfaceSsidRoaming(location, value, errors) {
 
 		function parseDomainIdentifier(location, value, errors) {
 			if (type(value) == "string") {
-				if (length(value) > 4)
-					push(errors, [ location, "must be at most 4 characters long" ]);
-
-				if (length(value) < 4)
-					push(errors, [ location, "must be at least 4 characters long" ]);
+				if (!matchUcMobility(value))
+					push(errors, [ location, "must be a valid Mobility Domain" ]);
 
 			}
 
diff --git a/ucentral.schema.full.json b/ucentral.schema.full.json
index 310b942..ef0112e 100644
--- a/ucentral.schema.full.json
+++ b/ucentral.schema.full.json
@@ -1683,8 +1683,7 @@
                                                 "domain-identifier": {
                                                     "description": "Mobility Domain identifier (dot11FTMobilityDomainID, MDID).",
                                                     "type": "string",
-                                                    "maxLength": 4,
-                                                    "minLength": 4,
+                                                    "format": "uc-mobility",
                                                     "examples": [
                                                         "abcd"
                                                     ]
diff --git a/ucentral.schema.json b/ucentral.schema.json
index 98e97a2..341794c 100644
--- a/ucentral.schema.json
+++ b/ucentral.schema.json
@@ -1145,8 +1145,7 @@
                 },
                 "domain-identifier": {
                     "type": "string",
-                    "maxLength": 4,
-                    "minLength": 4,
+                    "format": "uc-mobility",
                     "examples": [
                         "abcd"
                     ]
diff --git a/ucentral.schema.pretty.json b/ucentral.schema.pretty.json
index 463c5b5..09c6fbc 100644
--- a/ucentral.schema.pretty.json
+++ b/ucentral.schema.pretty.json
@@ -1293,8 +1293,7 @@
                 "domain-identifier": {
                     "description": "Mobility Domain identifier (dot11FTMobilityDomainID, MDID).",
                     "type": "string",
-                    "maxLength": 4,
-                    "minLength": 4,
+                    "format": "uc-mobility",
                     "examples": [
                         "abcd"
                     ]