Scope relationships exist between measure dimensions and regular dimensions. These are used to define the level at which the measures are available for reporting.
Scope relationships are not the same as joins in relational queries. There are no conditions or criteria in a scope relationship that dictate how a query is to be formed. A scope relationship only specifies if a fact can be queried with a specific dimension. If there is no scope relationship between the fact and the dimension, this will result in an error.
Once you set the scope relationship for a measure dimension, the settings apply to all measures within the measure dimension. If data is to be reported at different levels for each measure in a measure dimension, then you can set the scope for each measure.
When setting the scope for a measure you are specifying the lowest level that the data can be reported on.