1) Expanded returns null 2) Link is always valid, returns 204 if the value is null Remark: 1) is consistent with the representation of structural properties of other primitive type and with expanded single-valued navigation properties 2) is consistent with directly accessing a property that has the null value, directly accessing the raw value of a property that has the null value, and directly accessing a single-valued navigation property that has no entity related http://docs.oasis-open.org/odata/odata/v4.01/cs01/part1-protocol/odata-v4.01-cs01-part1-protocol.html#sec_RequestingIndividualProperties http://docs.oasis-open.org/odata/odata/v4.01/cs01/part1-protocol/odata-v4.01-cs01-part1-protocol.html#sec_RequestingaPropertysRawValueusingval http://docs.oasis-open.org/odata/odata/v4.01/cs01/part1-protocol/odata-v4.01-cs01-part1-protocol.html#sec_RequestingRelatedEntities