A computer system operating computer software for enabling interaction between a user and an interface surface. The computer system is configured to receive indicating data from a sensing device which is placed in an operative position relative to the interface surface to sense at least one coded data portion on or in the interface surface. The computer system then determines, using the indicating data, a determined identity, and retrieves, using the determined identity, a layout indicative of locations associated with corresponding identities. Then the computer system determines, using the layout and the determined identity, a determined location of the sensing device relative to the interface surface, and identifies, using the determined location, the at least one interactive element. The computer system is configured to operate the computer software at least partly in accordance with instructions associated with the at least one interactive element.