diff --git a/library/L1CTL_Types.ttcn b/library/L1CTL_Types.ttcn
index 759aafd18..3eb45aeaf 100644
--- a/library/L1CTL_Types.ttcn
+++ b/library/L1CTL_Types.ttcn
@@ -278,18 +278,22 @@ module L1CTL_Types {
 		uint8_t		maio,
 		uint8_t		n,
 		OCT1		padding,
-		bitstring	ma length(64)
+		bitstring       ma length(64)
 	} with { variant "" };
 
+	type union L1ctlArfcnHopU {
+		Arfcn		arfcn,
+		L1ctlH1		hopping
+		/* 4 bytes hsn/mail/n/padding + 64*16bit = 132 byte = 1056 bit */
+	} with { variant "PADDING(1056)" };
+
 	type record L1ctlDmEstReq {
 		GsmTsc		tsc,
 		uint8_t		h,
-		Arfcn		arfcn optional,
-		L1ctlH1		hopping optional,
+		L1ctlArfcnHopU	u,
 		L1ctlTchMode	tch_mode,
 		L1ctlAudioMode	audio_mode
-	} with { variant (arfcn) "PRESENCE(h = 0)"
-		 variant (hopping) "PRESENCE(h = 1)" };
+	} with { variant (u) "CROSSTAG(arfcn, h = 0; hopping, h = 1)" };
 
 	type record L1ctlReset {
 		L1ctlResetType	reset_type,
@@ -521,8 +525,9 @@ module L1CTL_Types {
 			dm_est_req := {
 				tsc := tsc,
 				h := 0,
-				arfcn := arfcn,
-				hopping := omit,
+				u := {
+					arfcn := arfcn
+				},
 				tch_mode := tch_mode,
 				audio_mode := t_L1CTL_AudioModeNone
 			}