For Tassie, from TheLaw.gov I've deleted some text, just to make it easier to read the important bits...
141. No overtaking, &c., to the left of a vehicle
(1) A driver (except the rider of a bicycle) must not overtake a vehicle to the left of the vehicle unless –
(c) the vehicle is stationary and it is safe to overtake to the left of the vehicle.
144. Keeping a safe distance when overtaking
A driver overtaking a vehicle –
must pass the vehicle at a sufficient distance to avoid a collision
with the vehicle or obstructing the path of the vehicle; and
must not return to the marked lane or line of traffic where the vehicle
is travelling until the driver is a sufficient distance past the
vehicle to avoid a collision with the vehicle or obstructing the path
of the vehicle.+
151. Riding a motor bike or bicycle alongside more than one other rider
(1) The rider of a motor bike or
bicycle must not ride on a road that is not a multi-lane road alongside
more than one other rider, unless subrule (3) applies to the rider.
(2) The rider of a motor bike or
bicycle must not ride in a marked lane alongside more than one other
rider in the marked lane, unless subrule (3) applies to the rider.
(3) The rider of a motor bike or bicycle may ride alongside more than one other rider if the rider is –
(a) overtaking the other riders; or
So in essence, in Tassie, it is legal to overtake to the left of a stationary vehicle, and it is legal to ride two abreast (or three abreast if one of them is overtaking). If there's any chance the traffic is moving, then it means your motorcycle is travelling abreast with a car, which is not allowed.
In many respects, every aspect of filtering is covered by legislation, but it's the interpretation on the ground that varies. technically, you should be indicating when crossing the white line, you can't cross the solid line on the approach to an intersection, you can't travel alongside a moving car, you can't cross the solid white line at the front of the intersection. But, if the line is broken, you are using your indicators (hard when filtering) and the traffic is stationary, then it shouldn't be a problem... In Tassie anyway.
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