Lane Splitting
From New Zealand Motorcycle Wiki
Lane Splitting is riding between lanes of moving traffic on motorways or dual carriageways and is governed by the rules regarding Passing on the left. Passing vehicles while lane splitting must be done on the right hand side of the vehicle being overtaken while travelling in the same lane (do not cross lane markings during the pass) unless the vehicles you are passing are stationary. Indicators must be used and as a general rule of thumb, travel no more than 20kmh faster than the surrounding traffic. It's a good idea to blend back into traffic at speeds over 60kmh to avoid unwanted attention.
Also refer to filtering.