What data types can I use in a RIA Services user profile?

I know that RIA Services is kind of picky about which types it will let you send across the wire. I've run across this several times in working on an internal line of business app.

I also know that ASP.Net profiles don't allow you to save Dictionaries (a limitation of the serializer). The common workaround for this is to create a custom class that derives from System.Collection.ObjectModel.KeyedCollection,开发者_运维问答 which can then be serialized. However, the RIA services layer doesn't seem too happy about this workaround.

In researching setting up user profiles for use with the DomainAuthenticationService, the tutorials and documentation tend to only use basic data types (int, string, etc.) and to never use anything more complicated.

Can anyone enlighten me on the exact restrictions on data type for this specific scenario?