Three patterns are permissible when writing quatrains out.
ABAB, AABB, and AAAA
Are proper forms, no matter how passe.
The scanning lines, we’re told, should always add to four
Not two, not three, and certainly not more.
Transgressions bold, though heartfelt at the core
Will turn the reader sad and make the critic roar.
And so we write mere doggerel at best,
Attempting vainly to succor and appease
The wizened pedants who instruct and test,
Elevating acumen in varying degrees.