ernet standard. draft-ietf-sip-rfcxxxxbis-xx.txt [...] draft-ietf-sip-rfcxxxxbis-00.txt Draft standard RFCxxxx (New RFC number) draft-ietf-sip-rfcxxxbis-xx.txt [...] draft-ietf-sip-rfcxxxxbis-00.txt Proposed standard RFCxxxx (New RFC number) draft-ietf-sip-title-xx.txt [...] draft-ietf-sip-title-01.txt draft-ietf-sip-title-00.txt Chapter 2 Naming conventions term the first release of an Internet draft version 00. Hence, draft-ietf-sip-call-flows-01.txt is the second version (version number 1) of this specific Internet draft belonging to the SIP working group. Individual contributions to a working group discussion that are not directly related to a working group item or that are preliminary versions of a draft on a working group item follow a slightly different naming conven- tion containing the author's name: for example, draft-schulzrinne-sip-911- 01.txt. Finally, Internet drafts and RFCs can be found in different formats (Post- Script, Portable Document Format [PDF], txt), but the definitive reference is always the ASCII text version. It includes all the figures, tables, illustra- tions, and diagrams contained in the specification. Figure 2-16 outlines the life cycle of an Internet standard. A new idea (e.g., a new protocol) is first documented in draft-ietf-sip-title-00.txt This very first draft evolves thanks to the feedback given by the community until it reaches the standard (STD) maturity level. However, not all the drafts reach the end of the standardization process shown in figure 2-16. Many drafts reach the proposed status, but just a few proposed RFCs become a draft standard later. Among those that become a draft standard, even fewer become Internet standards. It is common for a proposed RFC to gather feedback and to be re-issued as a proposed RFC again (with a new RFC number) rather than as a draft standard. In the following chapters we will study different protocols and extensions to protocols specified by the IETF. It is important to keep Figure 2-16 in mind in order to understand in which maturity 