[NTG-context] Symmetrical layer positioning?

Hello all, is there a "secret power switch" to tell ConTeXt that a particular layer has different positioning depending on wether it's on a left or right page? I can of course do it manually, either by changing the layer position on each page or by using two layers instead of one, but I wanted to know if there was a more straightforward way that I was missing. -- Giuseppe "Oblomov" Bilotta