sentences:  The letter bank form of cluing consists of a shorter word (or words) containing no repeated letters (an "isogram"), and a longer word or phrase built by using each of these letters (but no others) at least once but repeating them as often as necessary.This type of clue has been described by American constructors Joshua Kosman and Henri Picciotto, who write the weekly puzzle for The Nation.The shorter word is typically at least three or four letters in length, while the target word or phrase is at least three letters longer than the bank word.