A system comprising a beverage dispensing machine and at least one first type of exchangeable supply pack comprising a first type of doser (11;31) and a product to be supplied in the operation of the system, said system comprising one or more detection means for at least automatically detection of the presence of the first type of exchangeable supply pack and of the product in the first type of exchangeable supply pack said means comprising: a first interface (13; 73; 135A; 135B) for incorporation in a machine; a second interface on the first type of doser (11; 31) of the first type of exchangeable supply pack, operatively connectable to the first interface; a transmitter (3; 57) on the first interface for emitting radiation; a first detector (5; 69; 143) on the first interface for detecting presence of product in the first type of exchangeable supply pack; a second detector (7; 75) on the first interface for detecting presence of the first type of exchangeable supply pack; and wherein the second interface on the first type of doser (11; 31) is receivable between the transmitter (3; 57) and both the first and second detectors (5, 7; 69, 75; 143), to interfere with radiation emitted by the transmitter (3; 57), the second interface of the first type of doser (11; 31) comprising a first substantially transparent element (11A;49) which in use is positioned between the transmitter (3; 57) and the first detector (5; 69); and a second substantially opaque element (11B; 77) which in use is positioned between the transmitter (3; 57) and the second detector (7; 75), and wherein the system further comprises at least one second type of supply pack including a second type of doser acting as the second interface operatively connectable to the first interface (13; 73; 135A; 135B), and having first and second elements receivable between the transmitter (3; 57) and the first and second detectors (5, 7; 69, 75; 143) and to interfere with radiation emitted by the transmitter (3; 57), the second type of doser has both its first element and its second element substantially opaque. a first interface (13; 73; 135A; 135B) for incorporation in a machine; a second interface on the first type of doser (11; 31) of the first type of exchangeable supply pack, operatively connectable to the first interface; a transmitter (3; 57) on the first interface for emitting radiation; a first detector (5; 69; 143) on the first interface for detecting presence of product in the first type of exchangeable supply pack; a second detector (7; 75) on the first interface for detecting presence of the first type of exchangeable supply pack; and wherein the second interface on the first type of doser (11; 31) is receivable between the transmitter (3; 57) and both the first and second detectors (5, 7; 69, 75; 143), to interfere with radiation emitted by the transmitter (3; 57), the second interface of the first type of doser (11; 31) comprising a first substantially transparent element (11A;49) which in use is positioned between the transmitter (3; 57) and the first detector (5; 69); and a second substantially opaque element (11B; 77) which in use is positioned between the transmitter (3; 57) and the second detector (7; 75), and