ijabz:
I agree, and the great thing about defining on the relationship rather than the work itself it is solves the problem of how to handle when a work is part of multiple works (the 4 season problems). When you have two levels of works they usually can be considered to map to the work/movement, the difficulty is when there are additional levels such as Operas it can be difficult to work out what each part actually is so it would be very useful if the type can be defined on the part of relationship.
@ijabz Could you perhaps use the 4 seasons example and give us examples of how this would work on both the work-attributes and relationship-attributes options?