version 5 by Michael Callaghan
Section: Rules for Yes/No questions
We test the answer to yes/no questions using the phrase 'the decision understood'. The decision understood takes one of two values, 'Yes' or 'No'. 'Y' and 'N' are understood as Yes and No when the player types their response.
There are two default rules for processing the answers to yes/no questions.
The first rule, called the 'invalid yes/no reply rule' tests whether the player has entered Yes or No. If the player has not so responded, the outcome is retry if the question is a closed yes/no question or parse if the question is a closed menu question.
The last rule, called the 'default yes/no rule', has the outcome exit.