A clinician is using a diagnostic manual to determine if a patient's symptoms warrant a specific diagnosis. The clinician is carefully checking the patient's reported symptom count, the duration of the symptoms, and their impact on daily functioning against a specific checklist provided in the manual. Which section of the manual's entry for the disorder is the clinician most directly applying?

A clinical psychologist is evaluating a new client. First, she reads a general summary describing the essential nature of a potential disorder to see if it's a plausible fit for the client's situation. Next, she methodically goes through a specific checklist of symptoms, noting which ones the client has experienced for the required duration to formally confirm the diagnosis. Based on this process, the psychologist is differentiating between which two components of the disorder's entry in the standard diagnostic manual?