Enclosed rhyme (or enclosing rhyme) is the rhyme scheme ABBA (that is, where the first and fourth lines, and the second and third lines rhyme). Enclosed-rhyme quatrains are used in introverted quatrains, as in the first two stanzas of Petrarchan sonnets. ''(From John Milton: "Sonnet VII") "Exposure", by Wilfred Owen, also has a good example of enclosed rhyme.