Functions may optionally contain an EntitySetPath attribute, that specifies the entity set that returned entities belong to relative to the entity set of the binding parameter.
FunctionImports may optionally specify an EntitySet which is a specific entityset that returned entities belong to.
We are not explicit on how EntitySetPath is used for FunctionImports. It could be ignored, it could be the default if EntitySet is not specified, or it could be illegal to specify EntitySet if EntitySetPath is specified.
Same is true for Actions.