Ed, I haven't had much joy working with the V3 service samples at odata.org. They don't seem to comply with the "normative" V1-V3 spec:
http://download.microsoft.com/download/9/5/E/95EF66AF-9026-4BB0-A41D-A4F81802D92C/[MS-ODATA].pdf I particular, they seem to be some kind of hybrid between V3 and V4 specs that isn't specified anywhere (I call it OData 3.5, for want of a better name). For example, JSON annotations from the V3 service samples start with "odata.", but you cannot find that anywhere in the V3 spec. My best guess is that the V3 samples at odata.org are based on an early draft of the V4 spec. I would recommend using the V2 and V4 sample services, skipping V3.