How do professionals determine whether a child's autism is mild, moderate or severe?

[Shiner]

I can't find a description of which particular behaviors separate the different classifications of autism. Is there an actual list the professionals follow to make this decision or is it subjective?

 

[Mattshark]

There is nothing in the diagnostic manual used by healthcare professionals designating the severity of the autism, so that would be something being used by a particular professional or clinic as a descriptor. I would then think that it is a non-standardized description indicating something about the magnitude of the impairment.