On-demand horological display mechanism, including a plurality of primary mechanisms each capable of determining the value of a variable, and at least one actuator that can be maneuvered by a user for the selection of the display of the instantaneous values of a specific variable determined by one of the primary mechanisms, each display being performed by the cooperation of a moveable display including a hand or a disc, with a complementary display including at least one graduated index, where the display and/or the complementary display is common to all of the displays that the display mechanism may produce.