1. Each pantoum stanza must be four lines long.

2. The length is unspecified but the pantoum must begin and end with
   the same line.

3. The second and fourth lines of the first quatrain become the first
   and third lines of the next, and so on with suceeding quatrains.

4. The rhyming of each quatrain is _abab_.

5. The final quatrain changes this pattern.

6. In the final quatrain the unrepeated first and third lines are used in
   reverse as second and fourth lines.