From another topic about zig-zag crossings and filtering, I think there is a cross over between filtering and overtaking and it needs to be made clearer which is which. I think that filtering is moving between vehicles all moving or stationary but will move in the same direction, so on the motorway, a dual carriageway or one way street. It would also apply when on a single carriageway one lane in each direction when both directions are stationary or queuing and moving occasionally and slowly