In the context of OData the values Out and InOut don't make sense for edm:Parameter elements: only the return type is part of the response, so there's no way for the function import to modify the input parameter values.
In the context of OData the values Out and InOut don't make sense for edm:Parameter elements: only the return type is part of the response, so there's no way for the function import to modify the input parameter values.