st
  Network Working Group                                          G.  Scott
  INTERNET DRAFT                        Defense Information Systems Agency
                                                                 August
                                                             November 1996

                   Guide for Internet Standards Writers
                <draft-ietf-stdguide-ops-00.txt>
                     <draft-ietf-stdguide-ops-01.txt>

  Status of this Document

     This document is an Internet Draft.  Internet-Drafts  Internet Drafts are working
     documents of the Internet Engineering Task Force (IETF), its areas,
     and its working groups.  Note that other groups may also distribute
     working documents as Internet Drafts.

     Internet Drafts are draft documents valid for a maximum of six
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     munnari.oz.au (Pacific Rim).

   Distribution of this document is unlimited.

   This Internet Draft expires 21 February 23 May 1997.

  Abstract

     This document is a guide for Internet standard writers.  It defines
     those characteristics that make standards coherent, unambiguous,
     and easy to interpret.  Also, it singles out usage believed to have
     led to unclear specifications, resulting in non-interoperable
     interpretations in the past.  These guidelines are to be used with  |
     RFC 1543, "Instructions to RFC Authors."                            |

     This version of the document is a draft. It's  It is intended to
     generate further discussion and addition by the STDGUIDE working
     group.  Please send comments to stdguide@midnight.com or to the author. stdguide@midnight.com.

  Table of Contents

  1    Introduction . . . . . . . . . . . . . . . . . . . . . . . . .

  2    General Guidelines . . . . . . . . . . . . . . . . . . . . . .
  2.1  Protocol Description . . . . . . .
  2.2  Discussion of Security . . . . . .
  2.3  Level of Detail Detail. . . . . . . .
  2.4  Protocol Versions Versions. . . . . . .
  2.5  Decision History . . . . . . .
  2.6  Response to Behavior Out of Scope Scope. . . . . .
  2.7  The Liberal/Conservative Rule Rule. . . . . . . .

  2.8  Handling of Protocol Options . . . . . . . .
  2.9   BNF Notation  Indicating Requirement Levels. . . . . . . .                      |
  2.10 Notational Conventions . . . . . .                                |
  2.11 Implementation Experience Experience. . . . . . . . . .
  2.12 Glossaries . . . . . . . . . .                                    |

  3    Specific Guidelines Guidelines. . . . . . . . . . . . . . . . . . . . . .
  3.1  Packet Diagrams Diagrams. . . . . . . .
  3.2  Summary Tables . . . . . . . .
  3.3  State Machine Descriptions . . . . . . . . .

  4     Glossary
5    Document Checklist . . . . . . . . . . . . . . . . . . . . . .

  5    Security Considerations. . . . . . . . . . . . . . . . . . . .    |

  6     Author's Addresses    Working Group Chair's Address . . . . . . . . . . . . . . . .

  7    References . . . . . . . . . . . . . . . . . . . . . . . . . .

  CHANGES FROM PREVIOUS DRAFT. . . . . . . . . . . . . . . . . . . .     |

  1  Introduction

     This document is a guide for Internet standard writers.  It offers
     guidelines on how to write a protocol specification with clarity,
     precision, and completeness.  These guidelines are based on both
     prior successful and unsuccessful IETF specification experiences.
     These guidelines are to be used with RFC 1543, "Instructions to RFC |
     Authors," or its update.  Note that some guidelines may not apply   |
     in certain situations.

     The goal is to increase the possibility that multiple
     implementations of a protocol will interoperate.  Writing
     specifications to these guidelines will not guarantee
     interoperability.  However, a recognized barrier to the creation of
     interoperable protocol implementations is unclear specifications.

     Many will benefit from having well-written protocol specifications.
     Implementors will have a better chance to conform to the protocol
     specification.  Protocol testers can use the specification to
     derive unambiguous testable statements.  Purchasers and users of
     the protocol will have a better understanding of its capabilities.

  2  General Guidelines

     It is important that multiple readers and implementors of a
     standard have the same understanding of a document.  To this end,
     information should be orderly and detailed.  The following are
     general guidelines intended to help in the production of such a
     document.

  2.1  Protocol Description

     Standards track documents must include a description of the purpose |
     or context of a the protocol's use.  The author of a protocol
     specification will have a great deal of knowledge as to the purpose
     of a the protocol.  However, the reader is more likely to have
     general networking knowledge and experience, rather than expertise
     in a particular protocol.  Without an    An explanation of the purpose behind will     |
     give the reader a reference point for understanding the protocol interpreting it is far more difficult,    |
     and where it fits in the Internet.  The Draft Standard RFC 1583 was |
     recommended to the STDGUIDE working guide as providing a
  reader is more prone good       |
     example of this in it "Protocol Overview" section.                  |

     The protocol's general description should also provide information  |
     on the relationship between the different parties to error. the protocol.  |
     This can be done by showing typical packet sequences.               |

     This also applies to the algorithms used by a protocol.  A detailed
     description of the algorithms or citation of readily available
     references that give such a description is necessary.

  2.2 Discussion of Security

     If the Internet is to achieve its full potential in commercial,
     governmental, and personal affairs, it must assure users that
     deliveries of their information transfers are free from tampering
     or compromise.  Well-written security sections in standard protocol
     documents can do much to achieve that condition.  Implementors will
     find it easier to comply and do security.  Users can understand the
     security measures in place, and so have faith in the Internet.

     The security section should address several topics.  Very important is a
  description of  Every          |
     standards track document must discuss the security issues risks inherent   |
     in the protocol solves, and what issues
  remain unsolved.  The being specified.  After the document's author has   |
     set out the security risks the protocol is open to, he then must    |
     discuss the remedies offered.  Additionally, the effects the        |
     security measures have on the protocol's use and performance.  If
     possible, the discussion should address how much insurance the
     implementation of the security measures achieves.

  An author may not include

     When no security measures or considerations in are offered, the
  protocol standard.  If so, author must provide a detail    |
     detailed explanation why they did not is
  necessary. why.  This discussion could present the        |
     reasons why the security issues are unresolvable at this time.
     Alternatively, the author could present a case why security is
     unneeded when using the protocol.

     These security sections should be complete and stand alone. separate.  If        |
     security measures are part of the general protocol text, they will
     be difficult to find.  If the security measures are not clear they
     may not be implemented, nor will a user be assured that they exist.

     Finally, it is no longer acceptable that security sections consist
     solely of statements similar to:  "Security issues are not
     discussed in this RFC."
  2.3  Level of Detail

     The author should consider whether concise or verbose text what level of descriptive detail best    |
     conveys the protocol's intent.  Concise text has several
     advantages.  It makes the document easier to read.  Such text
     reduces the chance for conflict between different portions of the
     specification.  The reader can readily identify the required
     protocol mechanisms in the standard.  Also, it makes it easier to
     identify the requirements for protocol implementation.  A
     disadvantage of concise descriptions is that a reader may not fully
     comprehend the reasoning behind the protocol, and thus make
     assumptions that will lead to implementation errors.

     Longer descriptions may be necessary, however, necessary  to explain purpose,           |
     background, rationale, implementation experience, or to provide     |
     tutorial information.   This permits explanations at sufficient depth to insure
  understanding of helps the reader  understand the       |
     protocol.  Yet several dangers exist with lengthy text.  Finding
     the protocol requirements in the text is difficult or confusing.  An increased risk that the
     The same mechanism may have multiple descriptions, which leads to   |
     misinterpretations or conflict.  Lengthy text is a challenge to the
     attention span of some readers.  Finally, it is more difficult to
     comprehend, a consideration as English is not the native language
     of the many worldwide readers of IETF standards.

     One approach is to divide the standard into sections:  one
     describing the protocol concisely, while another section consists
     of explanatory text.  The STD 3/RFC 1122/RFC 1123 1812 and Draft         |
     Standard RFC 1583 provides examples of this method.                 |

  2.4  Protocol Versions

     Often the standard is specifying a new version of an existing
     protocol.  In such a case, the authors should detail the
     differences between the previous version and the new version.  This
     should include the rationale for the changes, for example,
     implementation experience, changes in technology, responding to
     user demand, etc.

  2.5  Decision History

     In standards development, reaching consensus requires making
     difficult choices.  Including  By including a discussion history and           |
     rationales for a decision decision, the author can prevent future revisiting |
     of these disagreements later, when the original parties have moved
     on.  Occasionally,  Also, the knowledge of the "why" is as useful to an            |
     implementor as the description of "how."  For example,  the         |
     alternative not taken may have been simpler to implement, so
     including the logic behind the choice may prevent future
     implementors from taking nonstandard shortcuts.

  2.6  Response to Out of Specification Behavior

  Recommend

     The STDGUIDE working group recommends that detail description of    |
     the actions taken in case of behavior that is deviant from or
     exceeds the specification be included.  This is an area where
     implementors often differ in opinion as to the appropriate
     response.  By specifying a common response, the standard author can strike
  a blow against
     reduce the law of unintended consequences. risk that different inplementations will come in to      |
     conflict.                                                           |

     The standard should describe responses to behavior explicitly
     forbidden or out of the boundaries defined by the specification.
     Two possible approaches to such cases are discarding, or invoking
     error-handling mechanisms.  If discarding is chosen, detailing the
     disposition may be necessary.  For instance, treat dropped frames
     as if they never were never received, or reset an existing connection or
     adjacency state.

     The specification should describe actions taken when critical
     resource or performance scaling limits are exceeded.  This is not
     necessary for every case.  It is necessary for cases where a risk
     of network degradation or operational failure exists.  In such
     cases, a consistent behavior between implementations is necessary.

  2.7  The Liberal/Conservative Rule

     A rule, first stated in RFC 791, recognized as having benefits in
     implementation robustness and interoperability is:

             "Be liberal in what you accept, and
               conservative in what you send."

     Or establish restrictions on what a protocol transmits, but have few
  restrictions be able |
     to deal with every conceivable error received.    Caution is urged  |
     in applying this approach in standards track protocols.  It has in  |
     the past lead to conflicts between vendors when interoperability    |
     fails.  The sender accuses the receiver of failing to be liberal    |
     enough, and the receiver accuses the sender of not being            |
     conservative enough.  Therefore, the author is obligated to provide |
     extensive detail on what it will receive. send and receive behavior.                      |

     To avoid any confusion between the two, recommend that standard
     authors specify send and receive behavior separately.    The effect of this approach is that the
     description of reception will require the most detailing.  For      |
     implementations will be expected to accept any packet from the
     network without failure or malfunction.  Therefore, the actions
     taken to achieve that result, need to be laid out in the protocol
     specification.  Standard authors should consider not just how to
     survive on the network, but achieve the highest level of
     cooperation possible to limit the amount of network disruption.
     The appearance of undefined information or conditions must not
     cause a network or host failure.  This requires specification on
     how to attempt acceptance of most of the packets.  Two approaches
     are available, either using as much of the packet's content as
     possible, or invoking error procedures.  Specify  The author should specify |
     a dividing line on when to take which approach.

     A case for consideration is that of a routing protocol, where
     acceptance of flawed information can cause network failure.  For
     protocols such as this, the specification should identify packets
     that could have differing interpretations and mandate that they be ignored.  |
     either rejected completely or the nature of the attempt to recover  |
     some information from them.  For example, routing updates that      |
     contain more data than the tuple count shows.  The protocol authors |
     should consider whether some trailing data can be accepted as       |
     additional routes, or to reject the entire packet as suspect        |
     because it is non-conformant.                                       |

  2.8  Handling of Protocol Options

     Standards with many optional features increase the chance of
     non-interoperable implementations.  The danger is that different
     protocol implementations may specify some optional combinations
     that are unable to interoperate with each other.  Ideally,
     implementation experience purges options from the protocol while
     the document moves along the standard track.

  Options

     Therefore, options should only be present in cases where the a protocol has an item that to          |
     support a particular marketplace requires, or because it enhances market, e.g., the product. financial industry, or       |
     network environment, e.g., a network constrained by limited         |
     bandwidth.  The protocol specification must explain the full        |
     implications of either using the option or not, and the case for
     choosing either course.  As part of this, the author needs to       |
     consider and describe how the options are intended to be used       |
     alongside other protocols.  However, omission of the optional item  |
     should have no interoperability consequences for the implementation
     that does so.

     Certain cases will require the specifying of mutually exclusive
     options within a protocol.  That is, the implementation of an
     optional feature precludes the implementation of the other optional
     feature.  For clarity,
  provide details on the author needs to state  when to implement |
     one or the other, what the effect of choosing one over the other
     is, and what problems the implementor or user may face.  The choice
     of one or the other options should have no interoperability
     consequences between multiple implementations.

  2.9 Indicating Requirement Levels                                      |

     The most prevalent current practice Internet-Draft draft-bradner-key-words-03.txt, "Key words for   |
     use in the specification of Internet RFCs to Indicate Requirement Levels," defines several words  |
     that can be used in many standards is track documents to identify signify the   |
     mandatory protocol features by from the term "MUST,"
  and optional features by "MAY" or "SHOULD."

2.9  Notational Conventions

  Formal syntax notations can of the       |
     specification.  The definitions provided are as they should be used to define complicated protocol concepts
  or data types, and also to specify values      |
     interpreted in implementing IETF standards.  Note that the force of |
     these data types.  This
  permits words is modified by the requirement level of the document in |
     which they are used.                                                |

     Some authors of existing IETF standards have chosen to capitalize   |
     these words to clarify or stress their intent, but this is not      |
     required.  What is necessary, is that these words are used          |
     consistently throughout the document.  That is, every mandatory or  |
     optional protocol requirement shall be identified by the authors    |
     and documented by these words.  If a requirement is not identified  |
     in this manner, it will not be considered an equal part of the      |
     protocol and be likely passed over by the implementor.              |

  2.10  Notational Conventions

     Formal syntax notations can be used to define complicated protocol
     concepts or data types, and to specify values of these data types.  |
     This permits the protocol to be written with out without concern on how the
     implementation is constructed constructed, or how the data type is represented
     during transfer.  The specification is simplifed simplified because it can be
     presented as "axioms" that will be proven by implementation.

     The formal specification of the syntax used should be referenced in
     the text of the standard.  Any extensions, subsets, alterations, or
     exceptions to the formal syntax should be defined.

     The STD 11/RFC 822 provides an example of this.  In RFC 822
     (Section 2 and Appendix D) the Backus-Naur Form (BNF) meta-language
     was extended to make its representation smaller and easier to
     understand.  Note, that the Internet-Draft                          |
     draft-ietf-drums-abnf-01.txt, "Augmented BNF for Syntax             |
     Specifications: ABNF," captures                                     |
     RFC 822's definition so that it can be used as a reference.         |
     Another example is STD 16/RFC 1155 (Section 3.2) where a subset of
     the Abstract Syntax Notation One (ASN.1) is defined.

2.10

     The author of a standards track protocol needs to consider several  |
     things before they use a formal syntax notation.  Is the formal     |
     specification language being used parseable by an existing machine? |
     If no parser exists, is there enough information provided in the    |
     specification to permit the building of a parser?  If not, it is    |
     likely the reader will not have enough information to decide what   |
     the notation means.  Also, the author should remember machine       |
     parseable syntax is often unreadable by humans, and can make the    |
     specification excessive in length.  Therefore, syntax notations     |
     cannot in place of a clearly written protocol description.          |

  2.11  Implementation Experience

     For a protocol to be designated a standard, it must go through the
     rigors of actual implementation.  This implementation experience
     should be captured in the final document.  For example, lessons
     learned from bakeoffs bake-offs between multiple vendors.

3  Specific Guidelines

  2.12  Glossary                                                         |

     Every standards track RFC should have a glossary, as words can have |
     many meanings.  By defining any new words introduced, the author    |
     can avoid confusing or misleading the implementer.  The following are guidelines definition  |
     should appear on how to present specific technical
  information in standards.

3.1 the word's first appearance within the text of the |
     protocol specification, and in a separate glossary section.         |

     It is likely that definition of the protocol will rely on many      |
     words frequently used in IETF documents.  All authors must be       |
     knowledgeable of the common accepted definitions of these           |
     frequently used words.  FYI 18/RFC 1983, "Internet Users'           |
     Glossary," provides definitions that are specific to the Internet.  |
     Any deviation from these definitions by authors is strongly         |
     discouraged.  If circumstances require deviation, an author should  |
     state that he is altering the commonly accepted definition, and     |
     provide rationale as to the necessity of doing so.  The altered     |
     definition must be included in the Glossary section.                |

     If the author uses the word as commonly defined, she does not have  |
     to include the definition in the glossary.  As a minimum,  FYI      |
     18/RFC 1983 should be referenced as a source.                       |

  2.13  Protocol Parameter Assignment                                    |

     The common use of the Internet standard track protocols by the      |
     Internet community requires that the unique values be assigned to   |
     the parameter fields.  The Internet Assigned Numbers Authority      |
     (IANA) is the central coordinator for the assignment of unique      |
     parameter values for Internet protocols.  The authors of a          |
     developing protocol that use a link, socket, port, protocol, etc.,  |
     need to contact the IANA to receive a number assignment.  For       |
     further information on parameter assignment and current             |
     assignments, authors should reference STD 2/RFC 1700, "Assigned     |
     Numbers."                                                           |

  3  Specific Guidelines

     The following are guidelines on how to present specific technical
     information in standards.

  3.1  Packet Diagrams

     Most link, network, and transport layer protocols have packet
     descriptions.
  Recommend   The STDGUIDE working group recommends that packet   |
     diagrams be included in the standard, as they are very helpful to
     the reader.  The preferred form for packet diagrams is a sequence
     of long words in network byte order, with each word horizontal on
     the page and bit numbering at the top:

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |Version| Prio. |                   Flow Label                  |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     In cases where a packet is strongly byte-aligned rather than
     word-aligned (e.g., when byte-boundary variable-length fields are
     used), display packet diagrams in a byte-wide format.  Use  The author   |
     can use different height boxes for short and long words, and broken |
     boxes for variable-length fields:

                         0 1 2 3 4 5 6 7
                         +-+-+-+-+-+-+-+-+
                         |    Length N   |
                         +-+-+-+-+-+-+-+-+
                         |               |
                         +    Address    +
                                ...
                         +   (N bytes)   +
                         |               |
                         +-+-+-+-+-+-+-+-+
                         |               |
                         +  2-byte field +
                         |               |
                         +-+-+-+-+-+-+-+-+

  3.2  Summary Tables

     The specifications of some protocols are particularly lengthy,
     sometimes covering a hundred pages or more.  In such cases the
     inclusion of a summary table can reduce the risk of conformance
     failure by an implementation through oversight.  A summary table
     itemizes what in a protocol is mandatory, optional, or prohibited.
     Summary tables do not guarantee conformance, but serve to assist an
     implementor in checking that they have addressed all protocol
     features.

     The summary table will consist of, as a minimum, four (4) columns:
     Protocol Feature, Section Reference, Status, and
     References/Footnotes.  Use
  additional  The author may add columns if they further   |
     explain or clarify the protocol.                                    |

     In the Protocol Feature column describe the feature, for example, a
     command word.  Group   We recommend grouping series of related             |
     transactions under descriptive headers, for example, RECEPTION.

     Section reference directs the implementor to the section,
     paragraph, or page that describes the protocol feature in detail.

     Status indicates whether the feature is mandatory, optional, or
     prohibited.
  Provide   The author can either use a separate column for each |
     possibility, or a single column with appropriate codes.  These
     codes need to be defined at the start of the summary table to avoid
     confusion.  Possible status codes:

        M  - must
        M - mandatory
        MN - must not
        O - optional
        S  - should
        X - prohibited
        SN - should not

  Use

     In the References/Footnotes column to  authors can point to other      |
     RFCs that are necessary to consider in implementing this protocol
     feature, or any footnotes necessary to further explain the implementation.

  RFCs 1122 and implementation
     further.

     The STD 3/RFC 1122/RFC 1123 provide provides examples of summary tables.

  3.3  State Machine Descriptions

     A convenient method of presenting a protocol's behavior is as a
     state-machine model.   That is, a protocol can be described by as a
     series of states resulting from a command, operation, or
     transaction.  State-machine models define the variables and
     constants that establish a state, the events that cause state
     transitions, and the actions that result from those transitions.
     Through these models, an understanding of the protocol's dynamic    |
     operation of the protocol  as sequence of state transitions that occur for any      |
     given event.  Detailed text description of the state machines event is
  necessary.  Also, recommend the use of possible.    State transitions can be detailed by    |
     diagrams, tables, or timelines time lines.                                    |

     Note that state-machine models are never to
  detail state transitions. take the place of       |
     detailed text description of the specification.  They are adjuncts  |
     to the text.  The protocol specification shall always take          |
     precedence in the case of a conflict.                               |

     When using a state transition diagram, show each possible protocol
     state as a box connected by state transition arcs.  Label  The author      |
     should label each arc with the event that causes the transition,    |
     and, in parentheses, any actions taken during the transition.  The
     STD 5/RFC 1112 provides an example of such a diagram.  As ASCII
     text is the preferred storage format for RFCs, only simple diagrams
     are possible.  Tables can summarize more complex or extensive state
     transitions.

     In a state transition table, read events vertically and states
     horizontally.  Represent    The form, action/new state, represents state       |
     transitions and actions in the form
  action/new-state.  Use commas to actions.  Commas separate multiple actions, and go on     |
     succeeding lines are used as required.  Present  The authors should present  |
     multiple actions in the order they must be executed, if relevant.
     Letters that follow the state indicate an explanatory footnote.
     The dash ('-') indicates an illegal transition.  The STD 51/RFC
     1661 provides an example of such a state transition table.  The
     initial columns and rows of that table are below as an example:

           | State
           |    0         1         2         3         4         5
     Events| Initial   Starting  Closed    Stopped   Closing   Stopping
     ------+-----------------------------------------------------------
      Up   |    2     irc,scr/6     -         -         -         -
      Down |    -         -         0       tls/1       0         1
      Open |  tls/1       1     irc,scr/6     3r        5r        5r
      Close|    0       tlf/0       2         2         4         4
           |
       TO+ |    -         -         -         -       str/4     str/5
       TO- |    -         -         -         -       tlf/2     tlf/3
     The STD 18/RFC 904 also presents state transitions in table format.
     However, it lists transitions in the form n/a, where n is the next
     state and a represents the action.  The method in RFC 1661 is
     preferred as new-state logical logically follows action.  Also, this RFC's  |
     Appendix C models transitions as the Cartesian product of two state
     machines.  This is a more complex representation that may be
     difficult to comprehend for those readers that are unfamiliar with
     the format.  Recommend   The working group recommends that authors present     |
     tables as defined in the previous paragraph.

     A final method of representing state changes is by a timeline.  The
     two sides of the timeline represent the machines involved in the
     exchange.
  List  The author lists the states the machines enter as time   |
     progresses (downward) along the outside of timeline.  Within the
     timeline, show the actions that cause the state transitions.  An
     example:

              client                                     server

                 |                                          |
                 |                                          |   LISTEN
     SYN_SENT    |-----------------------                   |
                 |                       \ syn j            |
                 |                        ----------------->|   SYN_RCVD
                 |                                          |
                 |                        ------------------|
                 |        syn k, ack j+1 /                  |
     ESTABLISHED |<----------------------                   |
                 |                                          |

  4  Glossary

  Internet standards are to use the following terms.  Deviations from the
  definitions given are discouraged, as it will likely cause
  misinterpretations among readers.

  MAY

  This word defines the existence of an item that is optional.

  MUST

  This word defines the existence of an item that is an absolute requirement
  of the specification.

  MUST NOT

  This phrase prohibits the use of the item.

  OPTIONAL

  This word specifies that implementation of an item is discretionary.

  RECOMMENDED

  This word specifies an item that there may exist valid reasons in
  particular circumstances to ignore.

  REQUIRED

  This word specifies an item that is an absolute requirement of the
  specification.

  SHOULD

  This word defines the existence of an item that there may exist valid
  reasons in particular circumstances to ignore.

  SHOULD NOT

  This phrase means that there may exist circumstances when the described
  behavior is acceptable or even useful.  Even so, describe the full
  implications so that the implementor can carefully weigh the pros and cons
  of the behavior.

  The above definitions are of a "contractual" nature.  This RFC does not
  define technical terms.  These definitions have been evolving with
  technology.  Extensive and detailed technical definitions in documents aid
  understanding.

5.0  Document Checklist

     The following is a checklist based on these suggestions which guidelines that can be  |
     applied to a document:

     o Does it explain the purpose of the protocol?
     o Does it reference or explain the algorithms used in the
       protocol?
     o Does it give packet diagrams in recommended form, if applicable?
     o Does it use the recommended meaning Internet meanings for any of the terms defined in use   |
       to specify the
     glossary above? protocol?                                          |
     o Are new or altered definitions for terms given in a glossary?     |
     o Does it separate explanatory portions of the document from
       requirements?
     o Does it describe differences from previous versions, if
       applicable?
     o Does it give examples of protocol operation?
     o Does it specify behavior in the face of incorrect operation by
       other implementations?
     o Does it delineate which packets should be accepted for
       processing and which should be ignored?
     o Does it consider performance and scaling issues?
     o How many optional features (MAY, SHOULD) does it specify?  If more than [X],
       does it separate them into option classes?
     o Have all combinations of options or option classes been examined
       for incompatibility?
     o Does it explain the rational and use of options?
     o If multiple descriptions of a requirement are given, does it
       identify one as binding?

6. Author's Addresses
     o Have all mandatory and optional requirements be identified and    |
       documented by the accepted key words that define Internet         |
       requirement levels?                                               |

  5.  Security Considerations                                            |

     This document does not define any security service or mechanism.  It|
     does call on IETF standards authors to define clearly the way the   |
     protocol they are specifying does or does not provide security      |
     assurances to the user.                                             |

  6  Working Group Chair's Address

     Gregor D. Scott
     Director, Defense Information Systems Agency
     ATTN: JIEO-JEBBD
     Ft. Monmouth, NJ  07703-5613
     USA

     Phone:  (908) 532-7726 427-6856                                              |
     Fax:    (908) 532-7723 532-0853                                              |
     EMail:  scottg@ftm.disa.mil

7.

  7  References

   RFC 791   "Internet Protocol (IP)," J. Postel, September 1981.

   RFC 904   "Exterior Gateway Protocol formal specification," D. Mills,

   RFC 1112  "Host extensions for IP multicasting," S. Deering,
               August 1989

   RFC 1122  "Requirements for Internet Hosts -- Communication Layers,"
               October 1989

   RFC 1123  "Requirements for Internet hosts -- Application and
               Support," October 1989

   RFC 1311  "Introduction to the STD Notes"

   RFC 1583  "OSPF Version 2"                                            |

   RFC 1602  "The Internet Standards Process - Revision 2"
   This Internet
   RFC 1700  "Assigned Numbers," J. Reynolds, J. Postel, October 1994    |

   RFC 1983  "Internet Users' Glossary"                                  |
   draft-ietf-drums-abnf-01.txt, "Augmented BNF for Syntax               |
     Specifications: ABNF," D. Crocker                                   |

   draft-bradner-key-words-03.txt, "Key words for use in RFCs to         |
     Indicate Requirement Levels," S. Bradner                            |
  CHANGES FROM PREVIOUS DRAFT

  Changes are marked by "|" along the right margin.  Many of the changes
  are editorial in nature.  Some were rewriting sentences for clarity.
  Others are noted as follows:

  1.   A reference to RFC 1543 was added to the Abstract and Introduction
  so that authors would know that this was not a stand alone document.
  That they had to comply to RFC 1543 as well.

  2.   In section 2.1, text recommending a "Protocol Overview" and a
  description of how the parties to the protocol relate was added.
  Reference to Draft expires 21 February 1997. Standard RFC 1583 was added.

  3.   In section 2.2, text was added calling for discussion of all the
  security risks a protocol faces, rather than just the security problems
  the protocol solves.

  4.   In section 2.7, cautionary text regarding the use of the
  liberal/conservative rule was added.

  5.   In section 2.8, text calling on authors to consider how protocol
  options are used with other protocols was added.

  6.   A new section, "2.9 Indicating Requirement Levels," was added to
  discuss the use of key words to identify protocol mandatory and option
  features.

  7.   In section 2.10, a reference to DRUMS work in defining ABNF, and
  cautionary text on using formal syntax notation was added.

  8.   A new section, "2.12 Glossary," was added calling on standards
  track protocol authors to include a glossary of new or revised terms.

  9.   A new section, "2.13 Protocol Parameter Assignment," calls on
  authors to get such assignments from IANA.

  10.  In section 3.3, a statement that text takes precedence over state
  machine models was added.

  11.  The previous draft's section 4, "Glossary," was deleted.  In its
  place, a reference to draft-bradner-key-words-03.txt is made in the new
  section 2.9.

  12.  New items were added to section 4, "Document Checklist," to reflect
  changes above.

  13.  A new section 5, "Security Considerations," was added.