 Roughly speaking, situations are highly structured parts of a system, such as a class session, a scene as seen from a certain perspective, a war, etc. Situations are the basic supporters of information. Infons, on the other hand, are the informational issues that situations may or may not support. The simplest kind of informational issue is whether some entities \(a_1 , \ldots ,a_n\) stand (or do not stand) in a relation \(R\) when playing the roles \(r_1 , \ldots ,r_n\), respectively. Such basic infon is usually denoted as 