Hi JProgrammer - I'm afraid I was seriously wrong in interpreting "USZ9 GST" as "US Zone 9, Greenwich Standard Time". This was an incorrect assumption on my part, as it made sense to me at the time. I apologize for putting out bad info. You are correct, this designation is very cryptic. I did a search on GST and found out that it stands for "Guam Standard Time", which I quite frankly never heard of, but then I am not a time zone "expert". I don't know why GST is being used as a reference, especially when nobody seems to be familiar with it.
You are also correct in stating that PST or PDT should 'normally' be used as a US time zone designation, however I don't believe I was incorrect to use GMT-8 in a discussion of how that zone relates to GMT and time zones in other parts of the world, just as you were not incorrect in referring to Melbourne as being GMT+10. These are the standard, universally understood designations for discussing and understanding our time zone system. In fact, GMT+10 makes immediate sense to me, whereas AEST I am less familiar with. I appreciate your bringing my error to light - sorry for confusing the issue. Now I know what GST stands for (now to find out how and why it is being used).