diff --git a/library/RLCMAC_CSN1_Types.ttcn b/library/RLCMAC_CSN1_Types.ttcn
index ee02a8a..20c2d81 100644
--- a/library/RLCMAC_CSN1_Types.ttcn
+++ b/library/RLCMAC_CSN1_Types.ttcn
@@ -416,6 +416,15 @@
 		variant (repeated_pageinfo) "PRESENCE(repeated_pageinfo_present = '1'B)"
 	};
 
+	/* 12.26 Extension Bits IE  */
+	type record ExtensionBits {
+		uint6_t		extension_length,
+		bitstring	spare_bits
+	} with {
+		variant (extension_length) "LENGTHTO(spare_bits) - 1"
+		variant (extension_length) "UNIT(bits)"
+	};
+
 	/* 11.2.28 Uplink Ack/Nack */
 	type enumerated ChCodingCommand {
 		CH_CODING_CS1		('00'B),
@@ -423,6 +432,15 @@
 		CH_CODING_CS3		('10'B),
 		CH_CODING_CS4		('11'B)
 	} with { variant "FIELDLENGTH(2)" };
+	type record UlAckNackGprsAdditionsRel99 {
+		BIT1			ext_pkt_ta_present,
+		BIT2			ext_pkt_ta optional,
+		boolean			tbf_est
+		/* TODO: Rel5 ,... */
+	} with {
+		variant (ext_pkt_ta)	"PRESENCE(ext_pkt_ta_present = '1'B)"
+		variant (tbf_est) 	"FIELDLENGTH(1)"
+	};
 	type record UlAckNackGprs {
 		ChCodingCommand		ch_coding_cmd,
 		AckNackDescription	ack_nack_desc,
@@ -431,12 +449,18 @@
 		BIT1			pkt_ta_present,
 		PacketTimingAdvance	pkt_ta optional,
 		BIT1			pwr_ctrl_present,
-		PowerControlParameters	pwr_ctrl optional
-		/* TODO: Extension Bits, Rel5 ,... */
+		PowerControlParameters	pwr_ctrl optional,
+		BIT1			extension_bits_present,
+		ExtensionBits		extension_bits optional,
+		BIT1			not_used ('0'B),
+		BIT1				rel99_present,
+		UlAckNackGprsAdditionsRel99	rel99 optional
 	} with {
 		variant (cont_res_tlli)	"PRESENCE(cont_res_tlli_present = '1'B)"
 		variant (pkt_ta)	"PRESENCE(pkt_ta_present = '1'B)"
 		variant (pwr_ctrl)	"PRESENCE(pwr_ctrl_present = '1'B)"
+		variant (extension_bits) "PRESENCE(extension_bits_present = '1'B)"
+		variant (rel99)		"PRESENCE(rel99_present = '1'B)"
 		variant (cont_res_tlli) "BYTEORDER(first)"
 	};
 	type record UlAckNackEgprs {