Message Transmission Protocol
摘要
This document defines a number of message fields beyond those discussed in RFC 561. The overall message format is compatible with RFC 561; it makes extensive use of the miscellaneous fileds defined within RFC 561. The purpose of this document is to establish ARPANET standards with regard to the syntax and semantics for these additional fields. It is fully expected that all fields discussed herein will not be automatically processed by all Message Servers; however, the standard is necessary so that sites which wish to make use of these fields have a standard to work with. This document attempts to tread the narrow line between features for human processing and features for machine processing. The general feeling is that the fields listed are useful to people even if automatic processing is not supplied. In most cases, machinereadable notations have been enclosed in angle brackets (<>) to allow easy non-ambiguous ways for automatic processes to know whether and where to look in any field. The entire specifications has been made excessively general to allow for experimentation. Future documents based on experience will try to be more specific. This is simply the next step following <RFC 561>. This document is contained in two sections. Section I contains the relevant parts of RFC 561 which define the basic message syntax. Section II lists the new (and existing) header fields together with their proposed uses. [Page 1] RFC 680 SECTION I: BASIC MESSAGE SYNTAX