The Clerk is the underlying vote-server that maintains the data for all eVote's interfaces. There is no other database server involved.
The Clerk is an object-oriented C++ specialized database server, specialized in that it can only serve vote data. It has no flexibility in the data types it can store as do general relational or object-oriented database servers.
What is lost in flexibility is gained in automation: control of each datum is given to the person who contributes it; the data are maintained completely automatically. The administrator is not involved.
There is also a gain in embed-ability. The Clerk provides an Application Programmer's Interface that allows reliable, state-of-the-art poll/vote/petition facilities to be built cheaply.
For more information about The Clerk and the eVote project, please see the eVote paper at the First European Conference on Voting and Rating on the Internet.