In Australia, there are differences from state to state in how one is diagnosed, using different criteria, past history, etc.
Here's my little story:
I was diagnosed by a psychologist, then a psychiatrist confirmed the diagnosis so I could be referred to appropriate services and such.
To diagnose, the Wechsler Abbreviated Scale of Intelligence, the Scales of Independent Behaviour - Revised and the DSM-IV-TR Criteria for Autism were used. The DSM-IV-TR criteria for autism differ from the criteria for Asperger's Syndrome. The criteria for autism includes qualitative impairments in communication in which I met one criterion.
If the person meets four or five criteria, a diagnosis of Asperger's Syndrome is considered, based on additional Gillberg criteria. If this diagnosis is not met, a diagnosis of Pervasive Developmental Disorder - Not Otherwise Specified (PDD-NOS) is considered.
People who meet three or fewer criteria do not receive a diagnosis within the Autism Spectrum.
I met eight criteria as well as the Additional DSM criteria.
[name omitted] meets sufficient DSM-IV-TR criteria for a diagnosis of High-Functioning Autism. Although [name omitted]'s presentation is also consistent with Asperger's Syndrome, Autism is rated first in the diagnostic hierarchy, so that a person who meets sufficient criteria for Autism receives this diagnosis rather than Asperger's Syndrome.
Conceptually, High-Functioning Autism and Asperger's Syndrome are very similar and on the same continuum, with severity level the main differentiator.
Yet everyone I know (admittedly not very many people) was diagnosed in a different way to me.
I think a review of all this is in order, so I agree with you, Sophist.
Those quotes are from my diagnostic report.