Open just one part of txt file

[Bellot Hervé]

Hi
I have a too big txt data file and i would like to open it piece by piece. I generaly use mgetl function. I can open the first piece of X lines (mgetl('filename.txt',x)) but i can't open the second piece from X to 2X lines.how can i do that?

I think i will have the same problem whith the result file. I search a solution for recording the result step by step in a file.

Thank for your help
Hervé