Taika gave us these kata pairings in 2000
The idea is that you train these katas back-to-back and that by so doing you will "naturally discover" techniques that are made up of movements from the two katas. In other words, these two kata have movements that lend themselves to creating a technique.
An easy definition of a technique is three (3) or more movements. Rarely does a technique come from sequential movements from a single kata.