diff --git a/library/GSM_RR_Types.ttcn b/library/GSM_RR_Types.ttcn
index b090d25..3d2f76a 100644
--- a/library/GSM_RR_Types.ttcn
+++ b/library/GSM_RR_Types.ttcn
@@ -445,13 +445,37 @@
 		variant (mobile_allocation) "PRESENCE(freq_par_len != 0)"
 */
 	};
-	type record IaRestOctHH {
-		BIT2			presence,
-		PacketUlAssign		ul optional,
-		PacketDlAssign		dl optional
+	type record SecondPartAssign {
+		BIT1		r99, /* H / L */
+		BIT1		presence optional,
+		BIT5		ext_ra optional
 	} with {
-		variant (ul) "PRESENCE(presence = '00'B)"
-		variant (dl) "PRESENCE(presence = '01'B)"
+		/* TODO: use 'CSN.1 L/H' attribute here */
+		variant (presence) "PRESENCE(r99 = '1'B)" /* H */
+		variant (ext_ra) "PRESENCE(presence = '1'B)"
+	};
+	type union PacketUlDlAssignUnion {
+		PacketUlAssign		ul,
+		PacketDlAssign		dl
+	};
+	type record PacketUlDlAssign {
+		BIT1			ass_disc,
+		PacketUlDlAssignUnion	ass
+	} with {
+		variant (ass) "CROSSTAG(dl, ass_disc = '1'B; ul, ass_disc = '0'B)"
+	};
+	type union PacketAssignUnion {
+		SecondPartAssign	spa,
+		PacketUlDlAssign	uldl
+	};
+	type record IaRestOctHH {
+		/* Packet Assignment discriminator:
+		 * Packet Uplink / Downlink Assignment (0)
+		 * Second Part Packet Assignment (1) */
+		BIT1			pa_disc,
+		PacketAssignUnion	pa
+	} with {
+		variant (pa) "CROSSTAG(spa, pa_disc = '1'B; uldl, pa_disc = '0'B)"
 	};
 	type record PacketUlAssignDyn {
 		uint5_t		tfi_assignment,
@@ -724,6 +748,88 @@
 		with { extension "prototype(convert) decode(RAW)" };
 
 
+	template PacketDlAssign tr_PacketDlAssign(template GprsTlli tlli) := {
+		tlli := tlli,
+		group1_present := ?,
+		group1 := *,
+		ta_index_present := ?,
+		ta_index := *,
+		tbf_starting_time_present := ?,
+		tbf_starting_time := *,
+		p0_present := ?,
+		p0 := *,
+		pr_mode := *
+	};
+
+	template IaRestOctets tr_IaRestOctets_DLAss(template PacketDlAssign dl_ass) := {
+		presence := '11'B, /* HH */
+		ll := omit, lh := omit, hl := omit,
+		hh := {
+			pa_disc := '0'B, /* Packet Assignment (0) */
+			pa := {
+				uldl := {
+					ass_disc := '1'B, /* Downlink Assignment (1) */
+					ass := { dl := dl_ass }
+				}
+			}
+		}
+	};
+
+	template PacketUlAssign tr_PacketUlDynAssign(template uint5_t tfi := ?,
+						     template BIT1 polling := ?,
+						     template uint3_t usf := ?,
+						     template BIT1 usf_granularity := ?,
+						     template ChCodingCommand cs := ?) := {
+		presence := '1'B, /* Dynamic Assignment */
+		dynamic := {
+			tfi_assignment := tfi,
+			polling := polling,
+			spare := '0'B, /* Dynamic Assignment (mandatory after Rel-4) */
+			usf := usf,
+			usf_granularity := usf_granularity,
+			p0_present := ?,
+			p0 := *,
+			pr_mode := *,
+			ch_coding_cmd := cs,
+			tlli_block_chan_coding := ?,
+			alpha_present := ?,
+			alpha := *,
+			gamma := ?,
+			/* TODO: add to parameters */
+			ta_index_present := ?,
+			ta_index := *,
+			tbf_starting_time_present := ?,
+			tbf_starting_time := *
+		},
+		single := omit
+	};
+
+	template PacketUlAssign tr_PacketUlSglAssign := {
+		presence := '1'B, /* Single Block Assignment */
+		dynamic := omit,
+		single := {
+			alpha_present := ?,
+			alpha := *,
+			gamma := ?,
+			padding := '01'B,
+			tbf_starting_time := ?
+		}
+	};
+
+	template IaRestOctets tr_IaRestOctets_ULAss(template PacketUlAssign ul_ass) := {
+		presence := '11'B, /* HH */
+		ll := omit, lh := omit, hl := omit,
+		hh := {
+			pa_disc := '0'B, /* Packet Assignment (0) */
+			pa := {
+				uldl := {
+					ass_disc := '0'B, /* Uplink Assignment (0) */
+					ass := { ul := ul_ass }
+				}
+			}
+		}
+	};
+
 	template (value) GsmRrMessage ts_IMM_ASS(uint8_t ra, GsmFrameNumber fn, TimingAdvance ta,
 						ChannelDescription ch_desc, MobileAllocation ma) := {
 		header := t_RrHeader(IMMEDIATE_ASSIGNMENT, 0),
@@ -802,6 +908,7 @@
 		}
 	};
 
+	/* TODO: introduce generic TBF Assignment template for DL and UL */
 	template ImmediateAssignment t_IMM_ASS_TBF_DL(template GprsTlli tlli) := {
 		ded_or_tbf := {
 			spare := ?,
@@ -822,28 +929,7 @@
 		req_ref := ?,
 		timing_advance := ?,
 		mobile_allocation := ?,
-		rest_octets := {
-			presence := '11'B,
-			ll := omit,
-			lh := omit,
-			hl := omit,
-			hh := {
-				presence := '01'B,
-				ul := omit,
-				dl := {
-					tlli := tlli,
-					group1_present := ?,
-					group1 := *,
-					ta_index_present := ?,
-					ta_index := *,
-					tbf_starting_time_present := ?,
-					tbf_starting_time := *,
-					p0_present := ?,
-					p0 := *,
-					pr_mode := *
-				}
-			}
-		}
+		rest_octets := tr_IaRestOctets_DLAss(tr_PacketDlAssign(tlli))
 	};
 
 	template GsmRrMessage t_RR_IMM_ASS_TBF_DL(template GprsTlli tlli) := {