Explanation Field
The value of a parameter may be determined by the answer to a question. When such a question is posed during consultation, the expert system user will have the option to ask ESTA to 'explain the question'. This explanation must be provided by the knowledge engineer in the explanation field. This field consists of the keyword explanation followed by an explanatory text. The syntax for the explanation field is:
<explanation field> ::= explanation <text expression>
Examples
parameter marital_status 'the people are married'
type category
explanation
'Marital status is determined by whether' &
'there exists a marriage certificate for' &
name ' and ' name_of_partner ' or not'
options
married,
unmarried.
question 'What is the marital status of ' name ' ?'
Notice that the explanatory text may contain parameters already associated with a value as well as parameters currently unevaluated. In the latter case ESTA will evaluate the parameter first and then use its value as part of the explanation.