Already posted elsewhere but I will reiterate the BFTA position
It was voted that there would be no change to the BFTA rules about kneeling.
However, it was agreed that shooters could use ankle rolls to establish opinions upon their future use.
This means that rules for the use of rolls will be defined in the Main Shoot Rules for 2016.
Briefly, any ankle roll will be allowed but you will not be able to use a bag when using the roll.
If you wish to provide your own flat mat to keep your knee off the floor then that's fine.
Present BFTA rules do not prevent the use of a roll but it's assumed that a bag is used.
If you want to start experimenting with a roll now then that's fine just don't use a bag as well