Thanks for the script. It works nicely. I shall be glad if you kindly explain how to use and change the code 3-$l, 3-$h. Does it have any relationship with the number of L and H in the string following printf? Do the $h (1..2) and $l (1..2) refer to 2 levels each for H and L? Actually I tried to learn making some alterations in the script like 4-$l, 5-$h, $h(1..3), $l(1..4) etc.in appropriate places but I could not understand. This is because I donot know why the terms are used and how to change them. I hope you won't mind explain the terms. Please suggest me some reference texts for further study.