The specific patient-related event to which a specimen collection or collections (and subsequently, any tests performed on that specimen) are related or affected by time, sequence, directive, intent, etc. Examples might include drug administration (peak and trough), beginning of fasting (lipids, FBS), glucose challenge (tolerances) or meal (postprandial), admission (pre- or post-admission studies), scheduled surgery/transfusion (compatibility testing), onset of symptoms (acute and convalescent), Last Menstrual Period (pregnancy test, Pap smear), lumbar puncture (CSF tubes 1, 2, and 3), treatment completion (test of cure, post-transfusion H&H), use/ingestion (BAT, toxicology), start of 24-hour urine pooling (creatinine clearance), etc.