The body nimbus perceptible to a sime caused by the presence of selyn, mathematically akin to the electric field surrounding an electron. The Selyn Field surrounds both the Sime and the Gen. Channels can estimate the amount of selyn carried by a Gen or renSime by zlinning their selyn field because the intensity of that field varies by concentration of selyn in the body.
The extent, texture and internal structure of a nager, a selyn field, is a product both of the basal selyn consumption rate, the genetic nature, the state of being junct, disjunct, or non-junct, emotional state, state of health, age, and the existence of active or potential Endowment.
A channel can, under some circumstances, read exactly (or sometimes only approximately) how much selyn a Gen or renSime is carrying. One channel may not be able to read the selyn fields of another channel, depending on their relative placement on the scale of Orders and whether the subject wants to be read accurately or not.