The ISchema interface is not mapped to any one database table, but represents Data Dictionary schema elements owned by a single schema owner (in _Owner). Currently, it supports only schema elements owned by PUB (the OpenEdge default owner). You do not typically need to use this object for regular schema reads and updates because the Get*( ) and Update*( ) service methods on ISequence and ITable also support PUB-owned objects.
The ISchema interface also provides support for both read and load of the schema from a .df file using dedicated methods of the DataAdminService, including the GetSchemaChanges( ) and UpdateSchemaChanges( ) methods (which load the schema into an ISchema, then into the database, respectively) and the LoadSchemaChanges( ) method (which loads the schema into the database in one operation. The benefit of the two-method approach is that the schema has a LoadOptions property that allows you to specify options for the load. ISchema also has a Partitions collection property that holds all new partitions created as a result of the load, allowing you to manage and allocate the new partitions, as needed.