sentry duty(n = noun.act) guard, guard duty, sentry go - the duty of serving as a sentry; "he was on guard that night"
is a kind of assignment, duty assignment

anti-dumping duty, breach of duty, civic duty, countervailing duty, customs duty, death duty, duty, duty assignment, duty period, duty tour, export duty, fatigue duty, fiduciary duty, filial duty, guard duty, import duty, jury duty, legal duty, line duty, line of duty, neglect of duty, off duty, on duty, point duty, sense of duty, sentry, sentry box, sentry go, shipboard duty, shore duty, stamp duty, tonnage duty, tour of duty