Daylight saving algorithms (slightly OT?)

Hi, I'm producing embedded equipment that needs to know about daylight saving, which was introduced in WA late last year. The WA arrangement is that clocks shift early in the last Sunday of a specified month. That's reasonably OK to program into an embedded device, the only nonvolatile config you need to put in is the changeover months, and then let the code work out the changeover day. My concern is that the rules may change to something else that would require me to reburn the code (much harder to do in this case). Is anyone aware of any sort of de-facto standard that exists for daylight saving changeovers, which specifies the rules, or limits to the rules? TIA