I found some information on the Australian scale for Aspergers at: http://www.aspennj.org/pdf/information/ ... ndrome.pdf
There are 24 questions and each is rated from 0 to 6. The instructions read "If the answer is yes to the majority of the questions in the scale, and the rating was between two and six (i.e.conspicuously above the normal range), it does not automatically imply the child has Asperger's Syndrome. However, it is a possibility and a referral for a diagnostic assessment is warranted."
So if you got 13 or more out of 24, that means you had "yes" to a majority of the questions and the recommendation is to refer for a diagnostic assessment. So 18/24 and 19/24 is consistent with Asperger's.
I don't really know why it says it is for Asperger's rather than autism because one of the questions asks " Late in acquiring speech?" and that is indicative of autism rather than Asperger's...