This document describes common industry representation practices for the usage of video signal type code points, as these properties are conveyed across video content production and distribution carriage systems.rd edition 2021-05 Information technology — Coding- independent code points — Part 4: Usage of video signal type code points Reference number ISO/IEC TR 23091-4:2021(E) ？ ISO/IEC 2021 ISO/IEC TR 23091-4:2021(E) COPYRIGHT PROTECTED DOCUMENT ？ ISO/IEC 2021 All rights reserved. Unless otherwise specified, or required in the context of its implementation,