===DSM-IV-TR and ICD-10 criteria===The most widely used criteria for diagnosing depressive conditions are found in the American Psychiatric Association's revised fourth edition of the "Diagnostic and Statistical Manual of Mental Disorders" (DSM-IV-TR), and the World Health Organization's "International Statistical Classification of Diseases and Related Health Problems" (ICD-10), which uses the name "depressive episode" for a single episode and "recurrent depressive disorder" for repeated episodes.
However, much more research is needed before these tests could be used clinically.