A shoulder has two bones – a wide blade bone and a long shank bone. Pocket-boning is removing the blade bone only. The ‘pocket’ left behind is then stuffed. Alternatively, you can remove both bones and roll the whole joint up with stuffing or flavouring inside. If you plan to do this method it really is just as easy to buy a boned joint.
To stuff a fully boned 1.6kg (3½lb) rolled joint you will need 250g (8oz) of stuffing. For stuffing a pocketed joint, as explained here, allow about 300g (10oz) stuffing.