<P> A rhyme scheme is the pattern of rhymes at the end of each line of a poem or song . It is usually referred to by using letters to indicate which lines rhyme; lines designated with the same letter all rhyme with each other . </P> <P> An example of the ABAB rhyming scheme, from "To Anthea, who may Command him Anything", by Robert Herrick: </P>

What is the rhyme scheme of these lines abab abba abcb abac