The Replication Server managing a database requires a function-string class. Replication Server provides function-string classes for Adaptive Server, and with its non-ASE data server support features, Replication Server provides function-string classes for all actively supported data servers.
Replication Server sends the gateway a command that it constructs by mapping runtime values into the function string supplied for the function. Depending on how the function string is written and the requirements of the data server, your gateway can pass the command directly to the data server or process it in some way before it sends the request to the data server. See the Replication Server Options documentation for the actively supported data servers.
See the Replication Server Administration Guide Volume 2 > Customizing Database Operations for a list of Replication Server system functions that your database gateway may need to process.