1	group1	test1	att1	val1
2	group1	test1	att2	val2
3	group1	test1	att3	val3
4	group1	test1	att4	val4
5	group1	test2	att1	val5
6	group1	test2	att2	val6
7	group1	test2	att3	val7
8	group1	test2	att4	val8
9	group2	test3	att1	val1
10	group2	test3	att2	val2
11	group2	test3	att3	val3
12	group2	test4	att1	val4
13	group2	test4	att2	val5
14	group2	test4	att3	val6
15	group1	\N	att1	val9
16	group1	\N	att2	val10
17	group1	\N	att3	val11
18	group1	\N	att4	val12