Give us a clue, I don't have one.......
I've 3 small trees, Aldi specials, no idea of the rootstock, all 3 years old. They are Golden Delicious, Cox's and Elstar.
They are beginning to get a little wayward, but I don't know which branches to take out. :-\
There is a guide for pruning bush or cordon trees here.
http://www.gardenaction.co.uk/fruit_veg_diary/fruit_veg_mini_project_september_2d_apple.asp
There is a Which magazine guide that covers common questions here.
http://www.which.co.uk/files/application/pdf/Apple%20pruning-445-106394.pdf
Only had my 2 apple trees in a year, now 3 & 4 yr old. No fruit last year, hopefully this one. I have not had to prune my apple trees as yet but I have saved these two sites in my favourites for a later reference as I am sure I will need.