FCP* seems to be separating out into three layers, these are: [* By FCP I also include the XML-RPC interface]
#1 Basic Standard insert/request along with pk generation stuff #2 Metadata Intercepts metadata documents and acts accordingly #3 Stacks Supports "stacks", these are a generic name for documents which are updated by appending a higher number each-time. Stacks may be public or private, private stacks are SSKs and can only be added to by the SSK's owner. Public stacks may be verified or unverified. Verified stacks are tied to a private stack which a server can use to indicate that an entry in a public stack has been read. This is useful for submission mechanisms. Finally, stacks may include features to make them more efficient such as combining them with DBRs. Stack support is useful since a client can request that a server perform a stack operation, which may take hours to complete, and terminate before the operation has completed. I plan to outline a spec for stacks in due-course, and present it here
