In those years -- 9th - 12th centuries -- when tanka was so fashionable, poets competing in contests revived an old Chinese form by linking tanka poems together in a novel way. The poem was "broken" in half so one author wrote the 5-7-5 part and another responded and finished the poem by adding his (mostly men did this though it was first done by a woman!) 7-7 part. Instead of stopping there, someone else wrote a new 5-7-5 poem to "answer" to the previous 7-7 link and they named the genre renga -- meaning linked elegance. This proved to be so much fun poets were soon writing poems of 1,000 and even 10,000 links.

~ as quoted elsewhere...


edit: yeahbut, ifn I understand this, the form is:

1. a 5/7/5 syllable construct
b. a 7/7 syllable link
iii. a 5/7/5 response

... then b & iii alternating until we change the steenkin rulze a few centuries down the track?