(BCP) is a sub-series of mandatory IETF RFCs not on standards track. For Your Information (FYI) is a sub-series of informational RFCs promoted by the IETF as specified in RFC 1150 (FYI 1). In 2011, RFC 6360 obsoleted FYI 1 and concluded this sub-series. Standard (STD) used to be the third and highest maturity level of the IETF standards track specified in RFC 2026 (BCP 9). In 2011 RFC 6410 (a new part of BCP 9) reduced the standards track to two maturity levels. Streams There are four streams of RFCs: IETF, IRTF, IAB, and independent submission. Only the IETF creates BCPs and RFCs on the standards track. An independent submission is checked by the IESG for conflicts with IETF work; the quality is assessed by an independent submission editorial board. In other words, IRTF and independent RFCs are supposed to contain relevant info or experiments for the Internet at large not in conflict with IETF work; compare RFC 4846, RFC 5742, and RFC 5744. Obtaining RFCs The official source for RFCs on the World Wide Web is the RFC Editor. Almost any published RFC can be retrieved via a URL of the form http://www.rfc-editor.org/rfc/rfc5000.txt, shown for RFC 5000. Every RFC is submitted as plain ASCII text and is published in that form, but may also be available in other formats. For easy access to the metadata of an RFC, including abstract, keywords, author(s), publication date, errata, status, and especially later updates, the RFC Editor site offers a search form with many features. A redirection sets some efficient parameters, example: rfc:5000. The official International Standard Serial Number (ISSN) of the RFC series is 2070–1721. Status Not all RFCs are standards. Each RFC is assigned a designation with regard to status within the Internet standardization process. This status is one of the following: Informational, Experimental, Best Current Practice, Standards Track, or Historic. Each RFC is static; if the document is changed, it is submitted again and assigned a new RFC number. Standards Track Standards-track documents are further divided into Proposed Standard and Internet Standard documents. Only the IETF, represented by the Internet Engineering Steering Group (IESG), can approve standards-track RFCs. If an RFC becomes an Internet Standard (STD), it is assigned an STD number but retains its RFC number. The definitive list of Internet Standards is the Official Internet Protocol Standards. Previously STD 1 used to maintain a snapshot of the