Thanks Geoff,
as clarification - the problem lies in there being two difference country codes - not that ours was missing.
There is the NATO code AS for Australia and the IHO code AU. The same applies for the UK where it is GB and UK respectively. This is because AML is a NATO initiative and considered to be linked to the military and not charting. We have also had allocated AN for Australian AML production through the IHO.
As a production agency will typically only produce for itself, it is not a big problem to edit the file manually, but in principle the software should use a lookup table to work this out for itself.
thanks again
John