The system-relation data type

The system-relation type distinguishes elements that are associated with a system rather than the particular part where the element appears. A value of only-top indicates that the element should appear only on the top part of the current system. A value of also-top indicates that the element should appear on both the current part and the top part of the current system. If this value appears in a score, when parts are created the element should only appear once in this part, not twice. A value of none indicates that the element is associated only with the current part, not with the system.