(registered 2020-03-18, last updated 2020-03-18) Type name: application Subtype name: atsc-dynamic-event-message Required parameters: N/A Optional parameters: N/A Encoding considerations: binary This media type may require non-transparent transfer encoding (such as base64 or Quoted-Printable) on transports not capable of handling binary. Security considerations: This media type identifies a dynamic event message, which is used to deliver a stream of dynamic events, such as a list of updated signaling tables. Events themselves are notifications saying that some action needs to be taken. Since actions can cause receivers to behave in fairly arbitrary ways, both integrity protection and source authentication, as referenced in A/336 Section 5.4, are required to prevent misleading of processors. This media type does not provide any confidentiality protection and instead relies on the transport protocol that carries it to provide such security. These protocols are referenced in A/336 Section 5.4. Dynamic event messages are retrieved from an event server by dereferencing a URL that is constructed by the Receiver using the process defined in A/344 Section 5.4 and is in a domain specified and administered under authority of ATSC. The only domain currently allowed is vp1.tv, as defined in A/336 Table 5.20. This mitigates additional general security considerations , as signaling resulting in an atsc-dynamic-event-message can only be resolved to a server having a valid, active registration with the VP1 Registrar. In addition to this, processors should make every effort to validate the origin against other transport signaling, if present. Interoperability considerations: ATSC A/336 specifies the format of conforming messages and the interpretation thereof. Published specification: This media type registration is an integral part of ATSC A/336, “Content Recovery in Redistribution Scenarios”, Annex E. The payload is defined in Section 5.1.8 of that document. This specification is available at www.atsc.org/standards. Applications that use this media type: ATSC 3.0 television and Internet encoders, decoders and other facility and consumer equipment. Additional information: N/A Person & email address to contact for further information: Editor, Advanced Television Systems Committee (jwhitaker&atsc.org) Intended usage: COMMON Restrictions on usage: N/A Author: ATSC. Change controller: ATSC.