Footnote

This may seem overly restrictive. However, many different kinds of knowledge can be represented in this way -- for example, it is true that A believes something; it is true that B would be true if C were true; it is true that D is definitely false. In the current release of SDML, there is no standard notation for any of these kinds of knowledge, and the modeller must create appropriate clause definitions. In a later release, it is planned to provide additional databases for things that are known to be false.