# Specifications and Architecture The following links reference the **official specification documents published by the Industrial Digital Twin Association (IDTA)**. They define the normative concepts, structures, and data models of the Asset Administration Shell (AAS) and its related elements. These documents are authoritative and should be consulted whenever implementation details, formal definitions, or compliance questions arise. * Introduction Provides an official overview of the Asset Administration Shell concept, its motivation, scope, and positioning within industrial digital twin architectures. * AAS Specification Defines the core structure and attributes of the Asset Administration Shell itself, including identification, administration, and lifecycle-related aspects. * Submodel Specification Describes the formal model of Submodels, which are used to structure domain-specific information within an AAS. * Submodel Element Specification Specifies the common attributes and rules that apply to all Submodel Elements, forming the foundation for consistent data representation. * Submodel Element Types Details the individual types of Submodel Elements (e.g., Properties, Collections, Relationships) and their intended usage. * Data Types Defines the primitive and complex data types used across the AAS metamodel, ensuring semantic and technical interoperability. * Control Component Type Official IDTA Submodel specification describing the standardized structure for modeling Control Component *types*. * Control Component Instance Companion specification defining how Control Component *instances* are represented based on the corresponding type definitions.