what is a common way poets create variations in pantoums?

Poets create variations in pantoums by changing words while still maintaining the rhyming structure. For example, in the first quatrain of a pantoum, the second and fourth lines may rhyme; in the second quatrain, those same lines may have the same words, but the first and third lines will rhyme; in the third quatrain, the pattern shifts once again, making the previously unchanged lines the rhyming lines, leaving only one original line (line four) until finally completing the pattern to form a circle of quatrains where the poem began the pattern in the form of the final quatrain. Additionally, some pantoums may also introduce small shifts in grammatical structure for various lines.