The "barcode" field in a service record identifies the marking on the associated equipment as used in an inventory system. The general form is 2 letters followed by 6 digits. CSCF's system is found at https://cs.uwaterloo.ca/cscf/internal/inventory/, MFCF's is found at https://www.math.uwaterloo.ca/inventory/login.php.
When specifying this field in a customized sort or display, use the name "equip_barcode".