Casual loading on overtime?

As a general rule, overtime payable to casual employees for overtime, or other work outside of ordinary hours where penalty rates might be called for, is calculated by reference to the rate for ordinary hours and not the causal rate which includes the standard 15% loading (which compensates casual employees for not having paid leave or guaranteed hours. However some industrial instruments provide that the rate is to include the penalty rate. An example is the Manufacturing and Associated Industries and Occupations Award 2010. Clause 14 of that modern award treats the casual loading of 15% as being included in what the awards terms the all purpose rate.