In most cases, a schema is created at design time in the Schema Designer, and used at run time without modifications. However, all schema objects are programmatically accessible at run time through the schema object model, with the C1.Data.SchemaObjects.Schema class being the root of that object model. Using this object model, it is possible to modify the schema or even define it from scratch at run time, using the CreateSchema event. To access and modify the Schema object, use the Schema property. In a 3-Tier Application, this event is called both for the client and server instances of the data library. If you modify schema in this event, you may need to know whether it occurs on the client or on the server, for example, to modify database connections differently depending on where the event occurs. This information can be obtained from the RunsAt property.

Reference

C1SchemaDef Class
C1SchemaDef Members
Schema Objects