The process of manipulating the Selyn fields surrounding the people in the area, blocking fields from being zlinnable. Only channels can do this because it requires the dual nervous system. Think of 3-D vision requiring two eyes.
A channel's first lessons are in manipulating the ambient -- or "working fields" as it is called in First Channel and Channel's Destiny where they are first discovering what a channel can do, empiracally, without a clue how or why it works.
(Source: Index card file. Unto Zeor, Forever) Ilyana modulating the shiltpron fields casting streamers of pure sensation, pinwheel of modulated colors. Gathered and focused the fields for Digen to take and send outward in a coruscating display of hyperconscious pyrotechnics and JOY.