On the left side of this image is a large cylinder-shaped object that represents a schema repository. Two squares within the schema repository represent schemas; one named Schema A, the other Schema B. Text entries in the Schema A square indicate that there are three versions of the schema. Text entries in the Schema B square indicate that there are two versions of that schema. To the right of the schema repository are three smaller cylinders that represent user databases. Two arrows from Version 3 of Schema A connect to two of the user databases. An arrow from Version 2 of Schema B connects to the other user database.