diff --git a/GSM48.st b/GSM48.st
index c97e5f7..55338b6 100644
--- a/GSM48.st
+++ b/GSM48.st
@@ -739,6 +739,17 @@ GSM48DataHolder subclass: GSM48Classmark3 [
     <gsmName: 'cm3'>
     <gsmElementId: 2r00100000>
     <gsmMinValueSize: 2 max: 12>
+
+    GSM48Classmark3 class >> createDefault [
+        <category: 'creation'>
+        ^ self new
+            data: self defaultValue; yourself
+    ]
+
+    GSM48Classmark3 class >> defaultValue [
+        <category: 'default'>
+        ^ #(16r60 16r14 16r4C 16r8F 16r60 16r3B 16r88 16r00 16r90) asByteArray.
+    ]
 ]
 
 GSM48VariableSizedIE subclass: GSM48MIdentity [