DSM-IV Diagnostic Criteria for Pervasive Developmental Disorder Not Otherwise Specified

This category should be used where there is a severe and pervasive impairment in the development of reciprocal social interaction associated with impairment in either verbal and nonverbal communication skills or with the presence of stereotyped behavior, interests, and activities but criteria are not met for a specific PDD, schizophrenia, schizotypal disorder or avoidant personality disorder.
 
It should be emphasized that PDD, NOS refers to autism and not to other conditions that are associated with impairments in social function and communicative functioning.

From the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition Text Revision (DSM-IV-TR). Washington DC: American Psychiatric Association; 2000:75.