ome of the working group. Issues can be raised at the IETF outside of the working group structure. When it's unclear whether a new problem set is or isn't a threat to the Internet or whether it warrants a working group, interested parties can hold a Birds Of Feathers (BOF) meeting. Area directors use BOFs to inves- tigate the issues at hand and assess interest within the community. The Technical Work Each working group has one or more chairs to manage progress and pro- cedures. Each working group also creates an official mailing list for public discussion of issues associated with the working group. Access to the mail- ing list is free and unrestricted, and archives are maintained as a matter of record. By now, most of the work done in a working group is carried out in the mailing list. Technical discussions about unresolved issues are conducted, agreements on procedures are reached, and general ques- tions about the technology being developed are posed. Working groups make decisions based on rough consensus. When individuals or groups of individuals differ on a certain matter, the dominant view prevails. (How to measure dominance is an ongoing debate for the IETF.) The view- point prevails that a decision is more important than a resolution of all differences. Chapter 2 IETF Specifications: RFCs and I-Ds The IETF publishes its documents in the RFC series. However, not all of the documents produced by IETF define standards. The RFC series has basi- cally three types of specifications: Internet standards track specifications, non-standards track specifications, and Best Current Practice (BCP) RFCs. Figure 2-15 shows the three types of specifications in the RFC series. The following sections examine each type. Standards Track RFCs RFCs following the standards track evolve through three maturity levels: proposed standard, draft standard, and stan- dard. Specifications coming out of a working group are classified as pro- posed standard when they are believed to be stable and well understood. Before reaching this leve