The description in the WM consists of a set of simple descriptions, or facts. These predicates must be pre-defined. These actions too must be pre-defined. The actions act on the working memory. This makes the IE independent of any particular domain.
Similar interpretations apply for other predicates.
These forms were chosen for improved readability. Here is a sample set of rules. Yours do not have to follow this form exactly. For the demonstration of your system you should use a simple working memory consisting of a list, or record, of attributes and values. The control of rule selection and execution works as follows.