Committee (RSOC) was created. In 2020, the IAB convened the RFC Editor Future Development program to discuss potential changes to the RFC Editor model. The results of the program included the RFC Editor Model (Version 3) as defined in RFC 9280 published in June 2022. Generally, the new model is intended to clarify responsibilities and processes for defining and implementing policies related to the RFC series and the RFC Editor function. Changes in the new model included establishing the position of the RFC Consulting Editor, the RFC Series Working Group (RSWG), and the RFC Series Approval Board (RSAB). It also established a new Editorial Stream for the RFC Series and concluded the RSOC. Requests for Comments were originally produced in non-reflowable text format. In August 2019 the format was changed so that new documents can be viewed optimally in devices with varying display sizes. Production and versioning The RFC Editor assigns each RFC a serial number. Once assigned a number and published, an RFC is never rescinded or modified; if the document requires amendments, the authors publish a revised document. Therefore, some RFCs supersede others; the superseded RFCs are said to be deprecated, obsolete, or obsoleted by the superseding RFC. Together, the serialized RFCs compose a continuous historical record of the evolution of Internet standards and practices. The RFC process is documented in RFC 2026 (The Internet Standards Process, Revision 3). The RFC production process differs from the standardization process of formal standards organizations such as International Organization for Standardization (ISO). Internet technology experts may submit an Internet Draft without support from an external institution. Standards-track RFCs are published with approval from the IETF, and are usually produced by experts participating in IETF Working Groups, which first publish an Internet Draft. This approach facilitates initial rounds of peer review before documents mature into RFCs. The RFC tradition of pragmatic, experience-driven, after-the-fact standards authorship accomplished by individuals or small working groups can have important advantages over the more formal, committee-driven process typical of ISO and national standards bodies. Most RFCs use a common set of terms such as "MUST" and "NOT RECOMMENDED" (as defined by RFC 2119 and RFC 8174), augmented Backus–Naur form (ABNF) (RFC 5234) as a meta-language, and simple text-based formatting, in order to keep the RFCs consistent and easy to understand. Sub-series The RFC series contains three sub-series for IETF RFCs: BCP, FYI, and STD. Best Current Practice