[crocee]

Is it possible for you to link to the pattern or a picture of it? I did a search and came up empty handed for the pattern.
I don't think it's Tunisian, you'd know it was not ordinary crochet because in Tunisian you work the stitches in two passes, the first picking them up and holding them on the needle much like knitting and the second to work them off. However, I have been wrong once or twice...maybe even three times in my life.

Tunisian simple stitch https://www.youtube.com/watch?v=WFdI5fc_iDE
This video is working in the back loop but maybe it will help you see what you need to do. https://www.youtube.com/watch?v=Tu2GzJHCgwE

HTH

Its not possible to link to the pattern due to copyright.

15th set down the page
http://www.shadylane.com/afghanspg2.htm

The picture suzeeq linked to looks the same but closeup.