Just found this whilst browsing the web, I found the last sentance very interesting -

Individual applications made directly to the Government of Malaysia for an award of the medal will be referred to Headquarters New Zealand Defence Force, for the assessment and verification of the individual's service.

The start date for the medal is 31 August 1957, because this is the date that Malaya / Malaysia became an independent nation.

ORDER OF WEAR
The PJM shall be worn immediately after the Korean issued War Service Medal and ahead of the INTERFET Medal if either is already held. If not it shall be worn as a foreign award