IBM Domino databases are built using the IBM Domino Designer client, available only for Microsoft Windows; standard user clients are available for Windows, Linux, and macOS. A key feature of IBM Notes is that many replicas of the same database can exist at the same time on different servers and clients, across dissimilar platforms; the same storage architecture is used for both client and server replicas. Originally, replication in Notes happened at document (i.e., record) level. With release of Notes 4 in 1996, replication was changed so that it now occurs at field level.