The term PAGE IN CONTRACT ON A SECURITY SYSTEM can be summarized as the process of signing a contract to install a security system. The crossword solution for this term is CAPTCHA, which stands for 'Completely Automated Public Turing test to tell Computers and Humans Apart'. This is a type of challenge-response test used in computing to determine whether or not the user is human. It is commonly used to prevent bots from accessing websites or other online services.