Just to fill in the blanks, here's what IDL does:
IDL> a = [[1,2,3,4], $
IDL> [5,6,7,8], $
IDL> [9,10,11,12], $
IDL> [13,14,15,16]]
IDL> print,a
1 2 3 4
5 6 7 8
9 10 11 12
13 14 15 16
IDL> print, a[[1,3],[0,3]]
2 16
--jh--