Function strings map Replication Server functions to data server commands for execution in a database.
For each replication definition, the primary Replication Server creates default function strings for the system functions with replication definition scope (rs_insert, rs_update, rs_delete, rs_select, and so on). These function strings are distributed with the replication definition to other qualifying Replication Servers with routes from the primary Replication Server.
Some circumstances may require you to create the function strings for system functions (that is, Replication Server does not create them for you).
See Replication Server Administration Guide Volume 2 > Customize Database Operations for details on function strings and function-string classes.