If they were exactly following such a periodic solution, then, at a conjunction of the two satellites, that is, when φ = 0, we would have l₁= 0, that is, Enceladus, which is on the inner of the two orbits, would be at perisaturnium, and alsol₂= π, so that Dione, which is on the outer of the two orbits, would be at aposaturnium.
Source: wiktionary