| capabilities? | readonly | TypeSpecLibraryCapabilities | Optional registration of capabilities the library/emitter provides | 
| diagnostics | readonly | DiagnosticMap<T> | Map of potential diagnostics that can be emitted in this library where the key is the diagnostic code. | 
| emitter? | readonly | object | Emitter configuration if library is an emitter. | 
| emitter.options? | public | JSONSchemaType<E> | - | 
| name | readonly | string | Library name. MUST match package.json name. | 
| requireImports? | readonly | readonly string[] | List of other library that should be imported when this is used as an emitter. Compiler will emit an error if the libraries are not explicitly imported. | 
| state? | readonly | Record<State,StateDef> | - |