The following prefixes are now extract in PyASN 1.5 from the MRT files -- in PyASN 1.2 they were left empty.
(File of 2014-05-13)


1.38.0.0/17	{38266}
5.128.0.0/14	{50923}
12.12.96.0/20	{32786}
20.137.0.0/21	{4237}
20.137.112.0/20	{4237}
20.137.160.0/20	{4237}
20.137.176.0/20	{4237}
20.137.240.0/20	{4237}
20.138.224.0/19	{4237}
20.139.64.0/20	{4237}
20.139.80.0/20	{4237}
20.148.0.0/20	{4237}
20.149.8.0/21	{17916}
37.52.0.0/14	{6877}
41.76.224.0/24	{36994, 11845}
41.128.132.0/22	{6127}
41.190.248.0/22	{37069}
41.196.28.0/22	{37193}
41.196.34.0/23	{37069}
42.106.0.0/15	{38266}
42.107.0.0/16	{38266}
46.200.0.0/14	{6877}
62.52.32.0/20	{61157}
62.52.48.0/21	{65000, 61157}
62.53.224.0/20	{61157}
63.123.80.0/21	{33482}
63.123.92.0/22	{7046}
64.58.160.0/19	{27426, 22814, 54710}
65.175.5.0/24	{7328}
65.183.0.0/20	{11580}
65.183.1.0/24	{11580}
65.183.15.0/24	{11580}
66.17.186.0/23	{29664}
66.79.224.0/19	{18997}
66.227.18.0/23	{27508}
66.227.112.0/20	{23491, 33684}
67.158.0.0/19	{20412}
67.158.32.0/20	{20412}
68.111.32.0/20	{12210}
68.225.16.0/20	{4323, 32351}
70.165.32.0/19	{64512, 64516, 11895, 64536, 3356, 701, 62620}
70.168.144.0/20	{36245}
70.168.248.0/21	{36343}
70.169.240.0/20	{46400, 36559}
72.2.239.0/24	{5666}
72.10.96.0/19	{22742}
72.28.99.0/24	{55028}
72.252.24.0/21	{11580}
84.235.107.0/24	{51375}
94.77.210.0/24	{48695}
94.124.216.0/21	{47798}
94.124.220.0/22	{47798}
98.124.0.0/18	{32881}
98.191.144.0/20	{4323, 32940}
103.20.188.0/22	{45731}
103.27.140.0/22	{132777, 45804, 18101, 24029}
112.79.32.0/21	{38266}
112.215.16.0/24	{17885}
112.215.26.0/24	{17885}
112.215.37.0/24	{17885}
112.215.71.0/24	{17885}
112.215.103.0/24	{17885}
116.193.160.0/22	{38546, 55410}
121.127.24.0/23	{6220}
123.63.40.0/21	{65001, 45635}
123.63.44.0/24	{65001, 45635}
123.63.112.0/21	{45916}
123.63.118.0/23	{45916}
125.7.20.0/24	{58418}
128.189.0.0/17	{393249}
156.154.160.0/24	{12008}
156.154.162.0/24	{12008}
162.212.40.0/24	{65600}
176.57.104.0/21	{41368}
176.104.191.0/24	{198820}
178.74.0.0/19	{35094}
179.127.160.0/19	{52664}
181.189.156.0/24	{52501}
183.203.0.0/16	{132510}
192.74.128.0/21	{21683}
192.88.191.0/24	{600}
192.88.192.0/24	{65033, 64811}
192.133.76.0/22	{35995}
193.231.48.0/20	{8708}
195.71.44.0/24	{61157}
195.71.152.0/21	{61157}
195.71.236.0/23	{61157}
196.205.24.0/22	{37069}
198.58.75.0/24	{20013}
198.135.216.0/24	{6058}
199.85.226.0/24	{6058}
199.193.100.0/22	{64526}
200.0.234.0/24	{22927}
200.5.226.0/24	{7303}
200.16.128.0/24	{7303}
200.41.128.0/21	{22927}
200.51.95.0/24	{22927, 7303}
200.51.96.0/24	{7303}
200.70.22.0/24	{7303}
200.133.192.0/18	{52888, 262742}
202.129.165.0/24	{38005}
202.152.245.0/24	{17885}
203.88.8.0/24	{38266}
203.205.144.0/22	{40000}
203.205.147.0/24	{40000}
203.205.148.0/22	{40000}
203.205.151.0/24	{40000}
207.35.39.0/24	{65404}
207.189.240.0/20	{6058}
208.83.88.0/23	{20148}
208.97.204.0/23	{46401}
209.120.212.0/24	{23029}
209.120.246.0/23	{53560}
209.159.192.0/18	{20412}
209.159.192.0/19	{20412}
209.159.224.0/21	{20412}
209.159.232.0/22	{20412}
209.159.240.0/20	{20412}
209.160.248.0/21	{53721}
211.138.96.0/20	{132510}
211.142.0.0/18	{132510}
211.142.30.0/23	{132510}
213.20.224.0/19	{61157}
213.131.67.0/24	{37339}
213.131.92.0/22	{37069}
213.186.96.0/19	{6877}
216.126.96.0/20	{6058}
217.114.48.0/20	{30847}
217.188.192.0/18	{61157}
221.131.0.0/18	{132510}
221.180.0.0/18	{132510}


AND ONE MORE NOT LISTED ABOVE - WHICH WAS SEQ/SET/SEQ - forgot the prefix.
[40191 6939 11164 10578 156 47065] {2381} [47065] =>> 47065
