API Reference > imodeljs-backend > Schema Schema Classes for working with ECSchemas Classes Name Description BisCoreSchema The BisCore schema is the lowest level Schema in an iModel. ClassRegistry The mapping between a BIS class name (in the form "schema:class") and its JavaScript constructor function Entity Base class for all Entities in an iModel. FunctionalSchema GenericSchema Schema Base class for all schema classes - see working with schemas and elements in TypeScript. Schemas Manages registered schemas Type Aliases Name Description EntityClassType Parameter type that can accept both abstract constructor types and non-abstract constructor types for instanceof to test. Last Updated: 15 June, 2021