THE Hongkong Securities Clearing Co has introduced a new function to help participants in the central clearing and settlement system (CCASS) to strengthen internal controls. The maker-checker function can provide an additional level of control over the acceptance of settlement instructions (SIs) which are input by CCASS participants for the settlement of non-exchange trades. It will require those SIs that exceed the transaction limit to be authorised by a checker before the system will accept them for processing. Participants may continue to operate under their present arrangements if they are satisfied that they offer adequate internal control and security. ''Close supervision of employees and checking of their activities remain necessary,'' said Richard Heckinger, chief executive. ''The maker-checker function will help prevent the unauthorised transfer of securities. ''The maker-checker function has been introduced as a result of operating experience since CCASS was launched in June last year. ''It is the first major system enhancement introduced and underlines our commitment to provide an efficient and cost-effective clearing and settlement service.''