The ISO 10303-221 is a STEP standard protocol for the exchange of intelligent schematics between different software applications. It can be used for instance for the exchange of P&ID's between an application of an EPC contractor and a plant owner or between an equipment supplier and an EPC contractor.
The protocol consists of a main AP with a number of STEP modules so that the structure is flexible and can be used in other STEP protocols.
The "AP221" as it is called in short, is designed to be used in conjunction with ISO15926-4 to ensure the intelligent data of the schematic are standardized as well.
The protocol with a main welcome page leading to the various modules and to explanatory notes can be downloaded here.
The document "How to Store Life-time Plant Data?" describes the principal capabilities of the new ISO standard AP221, its neutral format, flexibility and unconstrained storage capabilities. Furthermore it describes the reasons why conventional databases do not satisfy the (process) industry requirements for life time support of plant data.
Report "Guide on STEPlib, Guide for the creation, maintenance and use of Standard Data for Process Plants" documents the Library of Classes for Process Plant AP's in ISO 10303. The classes themselves, forming the content of the library, are available in electronic form as a set of spreadsheets on the STEP / Web Server
"Glossary of Terms"