A checkout system, comprising: 1.1 a bi-optical workstation operated by a clerk, the workstation having a first workstation window located in a horizontal plane, and a second workstation window located in an upright plane that intersects the horizontal plane, both of the workstation windows (12, 16) facing and being accessible to the clerk for enabling the clerk to pass products to be checked out in a transaction through the workstation to a bagging area, the bi-optical workstation comprising a raised housing portion having a front wall including the upright second workstation window and a rear wall opposite the front wall 1.2 the bi-optical workstation having a data capture arrangement (30, 32) for capturing through at least one of the workstation windows target data of targets associated with the products to be checked out by the clerk; 1.3 an accessory reader operated by a customer, the accessory reader being constituted as an accessory scan module having an accessory window lying in a vertical plane perpendicular to the horizontal plane of the first workstation window, intersecting the plane of the upright second window and facing the bagging area and being accessible to the customer for enabling the customer to interact with the accessory reader, 1.4 the accessory reader having a data capture assembly (66, 70) for capturing additional target data of additional targets associated with items related to the transaction; and 1.5 the bi-optical workstation further including structures that allow the same scan module be installed on the left side of the workstation or on the right side of the workstation, seen from the front of the workstation, including a rear cover having a first opening and a second opening located on opposite first and second side-walls of the rear cover symmetric about the center of the rear cover and being the same in size and shape to allow light from the additional targets entering the scan module through the accessory window, the left opening adapted for exposing the scan module if the scan module is installed on the left side of the workstation and the right opening adapted for exposing the scan module if the scan module is installed on the right side of the workstation, and mounting features and adapted to facilitate the installation of the scan module on either the left side of the workstation or the right side of the workstation, the mounting features (91L, 91R) being also reflectively symmetric about the center of the rear cover and the same in structure. 1.1 a bi-optical workstation operated by a clerk, the workstation having a first workstation window located in a horizontal plane, and a second workstation window located in an upright plane that intersects the horizontal plane, both of the workstation windows (12, 16) facing and being accessible to the clerk for enabling the clerk to pass products to be checked out in a transaction through the workstation to a bagging area, the bi-optical workstation comprising a raised housing portion having a front wall including the upright second workstation window and a rear wall opposite the front wall 1.2 the bi-optical workstation having a data capture arrangement (30, 32) for capturing through at least one of the workstation windows target data of targets associated with the products to be checked out by the clerk; 1.3 an accessory reader operated by a customer, the accessory reader being constituted as an accessory scan module having an accessory window lying in a vertical plane perpendicular to the horizontal plane of the first workstation window, intersecting the plane of the upright second window and facing the bagging area and being accessible to the customer for enabling the customer to interact with the accessory reader, 1.4 the accessory reader having a data capture assembly (66, 70) for capturing additional target data of additional targets associated with items related to the transaction; and 1.5 the bi-optical workstation further including structures that allow the same scan module be installed on the left side of the workstation or on the right side of the workstation, seen from the front of the workstation, including a rear cover having a first opening and a second opening located on opposite first and second side-walls of the rear cover symmetric about the center of the rear cover and being the same in size and shape to allow light from the additional targets entering the scan module through the accessory window, the left opening adapted for exposing the scan module if the scan module is installed on the left side of the workstation and the right opening adapted for exposing the scan module if the scan module is installed on the right side of the workstation, and mounting features and adapted to facilitate the installation of the scan module on either the left side of the workstation or the right side of the workstation, the mounting features (91L, 91R) being also reflectively symmetric about the center of the rear cover and the same in structure.