Internet DRAFT - draft-bormann-restatement
draft-bormann-restatement
Network Working Group C. Bormann
Internet-Draft Universität Bremen TZI
Intended status: Informational 2 March 2024
Expires: 3 September 2024
The Restatement Anti-Pattern
draft-bormann-restatement-01
Abstract
Normative documents that cite other normative documents often
_restate_ normative content extracted out of the cited document in
their own words.
The present memo explains why this can be an Antipattern, and how it
can be mitigated.
About This Document
This note is to be removed before publishing as an RFC.
Status information for this document may be found at
https://datatracker.ietf.org/doc/draft-bormann-restatement/.
Source for this draft and an issue tracker can be found at
https://github.com/cabo/restatement.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on 3 September 2024.
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Copyright Notice
Copyright (c) 2024 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Conventions and Definitions . . . . . . . . . . . . . . . 3
2. The Restatement Anti-Pattern . . . . . . . . . . . . . . . . 3
3. Reasons for making restatements . . . . . . . . . . . . . . . 4
3.1. Integrating a Complicated Base Standard Ecosystem . . . . 4
3.2. Trying to be a Textbook for the Implementer . . . . . . . 4
3.3. Increasing Availability from a Source with Restricted
Access . . . . . . . . . . . . . . . . . . . . . . . . . 4
3.4. Trying to Raise Attention to a Detail Deemed
Surprising . . . . . . . . . . . . . . . . . . . . . . . 5
3.5. Limitations in Formal Description Techniques . . . . . . 5
4. Perils of restatements . . . . . . . . . . . . . . . . . . . 5
5. Defusing restatements . . . . . . . . . . . . . . . . . . . . 6
5.1. Summary of Recommendations . . . . . . . . . . . . . . . 7
6. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 8
6.1. Example: Web linking RFC8288 . . . . . . . . . . . . . . 8
6.2. Example: Restatement of ISO8601:1988 in RFC3339 . . . . . 9
6.3. Example: Date-Time in YANG (RFC6991) . . . . . . . . . . 10
6.4. Example: ACME for Subdomains (RFC9444-to-be) . . . . . . 10
6.5. Example: Base64 Encoding variants in
draft-ietf-rats-eat-20 . . . . . . . . . . . . . . . . . 11
7. Security Considerations . . . . . . . . . . . . . . . . . . . 11
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 12
9.1. Normative References . . . . . . . . . . . . . . . . . . 12
9.2. Informative References . . . . . . . . . . . . . . . . . 12
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 15
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 15
1. Introduction
Normative documents that cite other normative documents often
_restate_ normative content extracted out of the cited document in
their own words.
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The present memo explains why this can be an Antipattern
[KOENIG][ANTIPATTERN], and how it can be mitigated.
1.1. Conventions and Definitions
Although this document is not an IETF Standards Track publication, it
adopts the conventions for normative language to provide clarity of
instructions to the implementer. The key words "MUST", "MUST NOT",
"REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT",
"RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in BCP 14 [BCP14] when,
and only when, they appear in all capitals, as shown here.
2. The Restatement Anti-Pattern
A _Restatement_ is the attempted expression of information that is
already expressed elsewhere.
In this document, we are mostly concerned with _Normative
Restatements_, i.e., statements that are intended (or look like they
are intended!) to be normative.
Restatements are rarely verbatim copies of the original statement and
the context needed to interpret that, so they tend to introduce
uncertainty about the interpretation of the restatement.
Authors often presume a reader is well-versed enough to infer that
such an uncertainty (or outright contradiction) is not intended and
how it is to be resolved. There is little reason to believe this is
actually the case.
An _internal restatement_ is a restatement of information that has
been provided previously in the document under discussion. Note that
an unambiguous internal reference is not a restatement, as it points
to the original text and its context. (There may still be
uncertainties how to interpret the internal restatement in the
additional context.)
A reference is _unambiguous_ if the previous passage is clearly
identified and delimited.
An _external restatement_ is a restatement of information that has
been provided in (one or more) external documents. Here there is
increased danger of an unclear scope of the reference, often by
pointing to an entire document where only a specific passage is
actually intended to be referenced.
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Restatements can be entirely _hidden_, i.e., there is no indication
that information given is a restatement. Restatements can also be
_explicit_ by clearly being identified as such, typically no longer
using normative language.
Restatements can be an Anti-Pattern because they can be "a common
response to a recurring problem that is usually ineffective and risks
being highly counterproductive" [WP-ANTIPATTERN]. Section 3
discusses the recurring problems as perceived by document authors,
Section 4 explains why restatements can be ineffective and
counterproductive, and Section 5 discusses how to use restatements in
a way that is not.
3. Reasons for making restatements
There are many reasons that cause document authors to include
restatements in their work, many of which are actually good reasons
once the perils of restatements are properly managed.
3.1. Integrating a Complicated Base Standard Ecosystem
Sometimes the source of the actual normative statement is complex and
would require considerable time to digest. A _simplifying_
restatement tries to shield the reader by rephrasing or summarizing
information from that source.
Such a restatement can be of good intention, or it can try to hide
complexity that the referencing document actually does make required
to incur.
3.2. Trying to be a Textbook for the Implementer
More generally, a restatement can attempt to be a directly useful
source for an implementer or user of a standard, e.g., by giving a
mere checklist of items (not necessarily complete!) that must be
implemented instead of actually identifying where the requirement and
possibly its finer points come from.
3.3. Increasing Availability from a Source with Restricted Access
In some cases, normative information from a cited document is not
openly available, but only under specific conditions that cannot be
expected to be satisfied by all users of the referencing document,
such as membership in an organization or payment of a non-trivial
fee. It may be appropriate to restate information from such a source
so the referencing document becomes useful.
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3.4. Trying to Raise Attention to a Detail Deemed Surprising
The author of the referencing document may see a need to alert the
reader to a detail of the cited document that might seem unintuitive
(i.e., not familiar) to the author. By restating the detail in terms
more familiar to readers of the referencing document, this alert can
be more useful.
3.5. Limitations in Formal Description Techniques
Formal description techniques (_FDT_, such as ABNF) are usually
designed to document a single specific artifact, not its evolution or
its embedding into another artifact. This can lead to wholesale
imports of FDT material, without indication whether just the FDT was
imported or whether the importing document is intended to evolve with
the donor document. See Section 6.1 and Section 6.3 for additional
illustration of this reason.
4. Perils of restatements
The danger of restatements is that they might not be exactly
expressing the same normative statement that the cited document
makes.
One form of this is the _incomplete_ restatement.
Abridged copies of a normative statement from the cited document
often leave open whether the abridgment is intentional: Is the
referencing document only importing some of the requirements of the
cited document? In the worst case, the restatement may appear to be
_forking an ecosystem_, i.e., an implementation of the cited document
cannot be used because it makes additional constraints that are not
meant to be included in the referencing document. (This peril of
course is also present with _intentional_ changes to the normative
statements in a cited document, but is likely to receive much more
attention during review.)
Section 6.5 presents an example for the situation where a reader
might infer behavior based on the common law statute interpretation
rule:
_"Expressio unius est exclusio alterius"_
which states that the reader is to presume that expressly referencing
one matter implies that other similar matters are intentionally not
mentioned and therefore are excluded. This is particularly
problematic with abridged statements, where this rule may be invoked
by the reader without an author being aware of it.
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Restatements may be slightly _semantically different_ from the cited
document, in particular if the latter is based on a relatively
inaccessible (possibly poorly documented or poorly developed)
terminology. Both authors and readers may not be aware that they
need to use tools that are commonplace in the ecosystem of the cited
document.
A large danger originates from restatements that are unclear whether
a _new_ normative requirement is intended or a just a restatement of
known normative requirements of the cited document. This is, of
course, particularly dangerous for _hidden_ restatements.
A restatement can cause _maintainability hazards_, as illustrated in
Section 6.1; it also can cause a referencing document to _decouple_
from the ecosystem of a cited document once that is repaired
(Section 6.3).
Finally, to readers familiar with the cited document, the restatement
can be surprising; if there really is no information in the
restatement, the reader automatically searches for a specific reason
this restatement is made and starts to reinterpret it until it means
something specific that would justify its presence. If the
restatement is not clearly identified as such, this is likely to
cause misinterpretations, as if the usage envisioned attempts to fork
the cited ecosystem. (Often, the people who need to interpret the
document in question are actually more familiar with the cited
document and the surrounding ecosystem than the authors of the
referencing document, who may just be pulling in the ecosystem to
solve one of their problems.)
5. Defusing restatements
A general recommendation for readers of a referencing document is
that they should try to detect restatements and read them in full
knowledge of their perils (Section 4). If a resolution is required,
the RFC errata process may provide a (poor) mechanism to obtain the
resolution and ensure it is documented in the context of the
referencing document. Mailing list discussions are also a good way
to obtain a resolution, but for additional readers they can be hard
to find, and, when found, it can be hard to extract any consensus
that was formed.
The rest of this section provides a summary of the recommendations
made by this document, employing RFC2119 keywords as an instruction
to the potential implementers of this document, i.e., document
authors and reviewers.
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Much of the danger of restatements can be averted if they are
sufficiently identified by the authors as such.
* For identification of internal restatements, use phrases such as:
In other words, hence, in particular, as discussed in Section NN.
* For identification of external restatements: As described/defined
in …, as per …
* In both cases, make sure that any local reference is clear and any
non-local reference is resolvable and well-scoped.
* Rephrasing the statement as a Note can make clear that there is no
normative intention.
* Examples MUST be identified clearly as such, including identifying
any explanatory notes as such so that these are not misunderstood
as new normative statements.
If a larger copy from a cited document is made, it SHOULD be made
verbatim and differences introduced deliberately should be explicitly
identified, possibly in a second step. Note that the FDT mechanisms
and their evolution can make verbatim copies less useful, in which
case a systematic approach of first copying and fixing and then, if
necessary, modifying can help the reader. For instance, [RFC2397]
uses a variant form of ABNF that can be parsed only once the variant
":=" syntax is replaced by "=". (This is an active specification and
was cited as recently as in Section 4.3 of [RFC9399], which provides
a clearly identified restatement in modern ABNF, with errata applied
and rules referenced from elsewhere added [we ignore the innocuous
redefinition of "hex" from "HEXDIG"].)
By making the copy informative, repairs from the base document (in
the [RFC2397] example e.g. [errata2397]) can be imported, even future
ones.
Where the copy is made because the cited document is not openly
available, this also often requires more processing than a verbatim
copy, increasing the probability of introducing errors and
misunderstandings. This can be somewhat mitigated by clearly stating
the purpose of a restatement, and the intended result when the
restatement and the original diverge.
5.1. Summary of Recommendations
(...Add nice checklist text for authors and reviewers based on
Section 5 later...)
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6. Examples
6.1. Example: Web linking [RFC8288]
This example is about an internal, FDT-induced restatement in
[RFC5988], which turned into an external restatement in [RFC6690],
which was not healed by the update to [RFC5988] in [RFC8288].
Section 5 of [RFC5988] defines a serialization of web links in a Link
Header Field. A link can have zero of more link-param parameters,
each of which has the form (simplified):
link-extension = parmname [ "=" ( ptoken / quoted-string ) ]
So link-extensions can always be written as a quoted-string, or,
alternatively, without quotes as a ptoken if the more limited
character repertoire of ptokens suffices.
However, [RFC5988] also defines the specifics of a few link
parameters. When simply inserting this into the overall ABNF, the
ABNF given for these link parameters needs to _restate_ the ABNF for
link parameters in their common syntax (simplified):
link-param = ( "rel" "=" relation-types )
/ ( "anchor" "=" <"> URI-Reference <"> )
/ ( "rev" "=" relation-types )
/ ( "hreflang" "=" Language-Tag )
/ ( "media" "=" ( MediaDesc / ( <"> MediaDesc <"> ) ) )
/ ( "title" "=" quoted-string )
/ ( "type" "=" ( media-type / quoted-mt ) )
This restatement loses the intended choice between ptoken and quoted-
string for many predefined link parameters, only keeping it for
"media" and "type" (and "rel" in the definition of relation-types,
which is arguably faulty by allowing non-ptoken characters in an
unquoted URI).
One could say that this restatement was caused by a limitation of
ABNF: ABNF cannot separately express both the overall syntax of link-
params (which yields the link-param value)) and the specific syntax
for the predefined link-params, contaminating the former with the
latter. The specific syntax would really need to be in terms of the
value yielded as opposed to _restating_ the link-param syntax that
yields the value.
Section 3 of [RFC8288] finally repairs this:
| link-param = token BWS [ "=" BWS ( token / quoted-string ) ]
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|
| Note that any link-param can be generated with values using either
| the token or the quoted-string syntax; therefore, recipients MUST
| be able to parse both forms. In other words, the following
| parameters are equivalent:
|
| x=y
| x="y"
|
| Previous definitions of the Link header did not equate the token
| and quoted-string forms explicitly; the title parameter was always
| quoted, and the hreflang parameter was always a token. Senders
| wishing to maximize interoperability will send them in those
| forms.
|
| Individual link-params specify their syntax in terms of the value
| after any necessary unquoting (as per [RFC7230], Section 3.2.6).
Unfortunately, [RFC6690] adds an external restatement copying from
[RFC5988] in defining a few more link-params (simplified):
link-param = ( "rel" "=" relation-types ) ; ...
/ ( "type" "=" ( media-type / quoted-mt ) )
/ ( "rt" "=" relation-types )
/ ( "if" "=" relation-types )
/ ( "sz" "=" cardinal )
cardinal = "0" / ( %x31-39 *DIGIT )
The letter of this specification for instance prohibits sz="47"
(requiring this to be represented as sz=47). The repair in [RFC8288]
cannot quite fix this as:
* it is not clear that the repair actually applies to [RFC6690] (a
general problem with updated ["obsoleted"] references)
* the ABNF in [RFC6690] would need to be rewritten to apply the rule
cardinal to the extracted value of the link-param.
6.2. Example: Restatement of [ISO8601:1988] in [RFC3339]
[RFC3339] was largely intended as a freely available restatement of
the paywalled [ISO8601:1988], with focus added on formally defining
the parts that might be useful in the Internet. However, when
[ISO8601:2000] introduced additional text that seemed to disallow the
syntax used for one extension that Section 4.3 of [RFC3339] had made
to the semantics of [ISO8601:1988], the precedence remained unclear.
Implementers of Internet-related standards largely ignored the
additional semantics of that extension anyway, while implementers of
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[ISO8601:1988] in general often performed input validation that made
sure the extension made by [RFC3339] wouldn't work. (This is only
now being addressed by Section 2 of
[I-D.ietf-sedate-datetime-extended].)
6.3. Example: Date-Time in YANG (RFC6991)
[RFC6991] defines a YANG type date-and-time on page 11, restating
parts of [RFC3339] (the restatement is also faulty in its item (b),
with an attempted cleanup in [I-D.ietf-netmod-rfc6991-bis]). Now
that [RFC3339] is being bug-fixed via Section 2 of
[I-D.ietf-sedate-datetime-extended], it is not clear whether the
change applies to the YANG type as well. This is more of a problem
for YANG than it might be otherwise, as it might trigger the YANG
concept of a "non-backwards-compatible" change to that datatype — a
problem that is not entirely _caused_ by restatements but gets much
harder to discuss.
6.4. Example: ACME for Subdomains (RFC9444-to-be)
A late draft of what became [RFC9444] defines a new feature added to
[RFC8555], referencing the base standard in a number of places.
Reviewing the draft [I-D.draft-ietf-acme-subdomains-04],
[acme-comment] states:
## restatement vs. new normative content
Providing a specification of a new feature added to ACME, the text
explains a number basic ACME mechanisms that are relevant to this
specification.
One pervasive problem is that these restatements of RFC 8555
content are not always easy to distinguish from new, normative
statements made by this document. E.g., 4.2 contains a statement
about "is defined" that is part of a paragraph restating RFC 8555
-- this one, however, appears to be new normative content.
(Languagetool diagnoses overuse of passive voice, which
exacerbates this problem.)
(The first paragraph of section 4 repeats the last paragraph of
section 3. But that is not a problem; redundancy can be good if
it improves the flow, and this is clearly labeled as a
restatement.) The introduction of section 4 is a summary/
restatement of RFC 8555; section 4.1 introduces new normative
content without warning (and leads the reader astray by actually
referencing RFC 8555).
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(These problems were ultimately addressed in [RFC9444].)
6.5. Example: Base64 Encoding variants in draft-ietf-rats-eat-20
Base64 encoding is defined in [RFC4648], but comes in a number of
variants. These often have default settings that are to be used
"unless the specification referring to this document explicitly
states otherwise" (e.g., Section 3.2 of [RFC4648]).
Documents that reference [RFC4648] normatively are surprisingly often
sloppy in doing so. Not [I-D.draft-ietf-rats-eat-20]: Its Section 2
(terminology) defines the term "Base64url Encoding”, referencing
[RFC4648] as well as [RFC7515] to fill in the open questions from
[RFC4648] (i.e., Section 5 and not Section 4, no '=' padding that
would be default, no extra characters).
While this was a good start, incomplete restatements in the following
text cause a problem [rats-comment]:
| A term "base64url encoded” [...] is used in multiple places. One
| of the places restates its own reference to RFC 4648, but doesn’t
| restate the reference to RFC 7515 and the text required with that.
| This restatement is very misleading as it strongly implies RFC
| 7515 is _not_ used here; the reference needs to be removed. In
| the other places I find the term is simply used, which assumes the
| reader will think to look up the term in the terminology [...]
(The problem in the draft was quickly addressed in the next
revision.)
7. Security Considerations
Restatements about security requirements and properties can create
the same uncertainties and interoperability problems as restatements
in other contexts. Security considerations sections have turned out
to be an attractor for such problems. They are meant "both to
encourage document authors to consider security in their designs and
to inform the reader of relevant security issues" (Section 1 of
[RFC3552]). In practice, they tend to be the first point in a
document that security issues are considered at all, so they often
both contain normative statements that are nowhere else in the
document and security-conscious restatements of other normative
statements in the document, the latter with all the perils that this
memo is about. The fact that security considerations sections are
often heavily fleshed out during IESG processing can exacerbate the
problem.
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8. IANA Considerations
This document has no IANA actions.
9. References
9.1. Normative References
[BCP14] Best Current Practice 14,
<https://www.rfc-editor.org/info/bcp14>.
At the time of writing, this BCP comprises the following:
Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
9.2. Informative References
[acme-comment]
Bormann, C., "[Last-Call] Artart last call review of
draft-ietf-acme-subdomains-04", 23 November 2022,
<https://mailarchive.ietf.org/arch/msg/last-call/
v0RYQkByhAII9yvaD6gbKWx0WtA>.
[ANTIPATTERN]
"Anti Pattern", C2 Wiki (Last edited:), 21 November 2012,
<http://wiki.c2.com/?AntiPattern>.
[errata2397]
"RFC Errata Report » RFC Editor", search result, n.d.,
<https://www.rfc-editor.org/errata/rfc2397>.
[I-D.draft-ietf-acme-subdomains-04]
Friel, O., Barnes, R., Hollebeek, T., and M. Richardson,
"ACME for Subdomains", Work in Progress, Internet-Draft,
draft-ietf-acme-subdomains-04, 29 June 2022,
<https://datatracker.ietf.org/doc/html/draft-ietf-acme-
subdomains-04>.
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[I-D.draft-ietf-rats-eat-20]
Lundblade, L., Mandyam, G., O'Donoghue, J., and C.
Wallace, "The Entity Attestation Token (EAT)", Work in
Progress, Internet-Draft, draft-ietf-rats-eat-20, 13 June
2023, <https://datatracker.ietf.org/doc/html/draft-ietf-
rats-eat-20>.
[I-D.ietf-netmod-rfc6991-bis]
Schönwälder, J., "Common YANG Data Types", Work in
Progress, Internet-Draft, draft-ietf-netmod-rfc6991-bis-
15, 23 January 2023,
<https://datatracker.ietf.org/doc/html/draft-ietf-netmod-
rfc6991-bis-15>.
[I-D.ietf-sedate-datetime-extended]
Sharma, U. and C. Bormann, "Date and Time on the Internet:
Timestamps with additional information", Work in Progress,
Internet-Draft, draft-ietf-sedate-datetime-extended-11, 23
October 2023, <https://datatracker.ietf.org/doc/html/
draft-ietf-sedate-datetime-extended-11>.
[ISO8601:1988]
ISO, "Data elements and interchange formats — Information
interchange — Representation of dates and times",
ISO 8601:1988, June 1988,
<https://www.iso.org/standard/15903.html>. Also available
from <https://nvlpubs.nist.gov/nistpubs/Legacy/FIPS/
fipspub4-1-1991.pdf
(https://nvlpubs.nist.gov/nistpubs/Legacy/FIPS/
fipspub4-1-1991.pdf)>.
[ISO8601:2000]
ISO, "Data elements and interchange formats — Information
interchange — Representation of dates and times",
ISO 8601:2000, December 2000,
<https://www.iso.org/standard/26780.html>.
[KOENIG] Koenig, A., "Patterns and Antipatterns", J. Object
Oriented Program. 8(1): pp. 46-48, 1995.
[rats-comment]
Bormann, C., "Re: [Rats] I-D Action: draft-ietf-rats-eat-
20.txt", n.d.,
<https://mailarchive.ietf.org/arch/msg/rats/
H8qXwQywD0W6x4QcC9Iwd5LYl2s>.
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[RFC2397] Masinter, L., "The "data" URL scheme", RFC 2397,
DOI 10.17487/RFC2397, August 1998,
<https://www.rfc-editor.org/rfc/rfc2397>.
[RFC3339] Klyne, G. and C. Newman, "Date and Time on the Internet:
Timestamps", RFC 3339, DOI 10.17487/RFC3339, July 2002,
<https://www.rfc-editor.org/rfc/rfc3339>.
[RFC3552] Rescorla, E. and B. Korver, "Guidelines for Writing RFC
Text on Security Considerations", BCP 72, RFC 3552,
DOI 10.17487/RFC3552, July 2003,
<https://www.rfc-editor.org/rfc/rfc3552>.
[RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data
Encodings", RFC 4648, DOI 10.17487/RFC4648, October 2006,
<https://www.rfc-editor.org/rfc/rfc4648>.
[RFC5988] Nottingham, M., "Web Linking", RFC 5988,
DOI 10.17487/RFC5988, October 2010,
<https://www.rfc-editor.org/rfc/rfc5988>.
[RFC6690] Shelby, Z., "Constrained RESTful Environments (CoRE) Link
Format", RFC 6690, DOI 10.17487/RFC6690, August 2012,
<https://www.rfc-editor.org/rfc/rfc6690>.
[RFC6991] Schoenwaelder, J., Ed., "Common YANG Data Types",
RFC 6991, DOI 10.17487/RFC6991, July 2013,
<https://www.rfc-editor.org/rfc/rfc6991>.
[RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Message Syntax and Routing",
RFC 7230, DOI 10.17487/RFC7230, June 2014,
<https://www.rfc-editor.org/rfc/rfc7230>.
[RFC7515] Jones, M., Bradley, J., and N. Sakimura, "JSON Web
Signature (JWS)", RFC 7515, DOI 10.17487/RFC7515, May
2015, <https://www.rfc-editor.org/rfc/rfc7515>.
[RFC8288] Nottingham, M., "Web Linking", RFC 8288,
DOI 10.17487/RFC8288, October 2017,
<https://www.rfc-editor.org/rfc/rfc8288>.
[RFC8555] Barnes, R., Hoffman-Andrews, J., McCarney, D., and J.
Kasten, "Automatic Certificate Management Environment
(ACME)", RFC 8555, DOI 10.17487/RFC8555, March 2019,
<https://www.rfc-editor.org/rfc/rfc8555>.
Bormann Expires 3 September 2024 [Page 14]
Internet-Draft The Restatement Anti-Pattern March 2024
[RFC9399] Santesson, S., Housley, R., Freeman, T., and L. Rosenthol,
"Internet X.509 Public Key Infrastructure: Logotypes in
X.509 Certificates", RFC 9399, DOI 10.17487/RFC9399, May
2023, <https://www.rfc-editor.org/rfc/rfc9399>.
[RFC9444] Friel, O., Barnes, R., Hollebeek, T., and M. Richardson,
"Automated Certificate Management Environment (ACME) for
Subdomains", RFC 9444, DOI 10.17487/RFC9444, August 2023,
<https://www.rfc-editor.org/rfc/rfc9444>.
[WP-ANTIPATTERN]
"Anti-pattern", Wikipedia page (at the time of writing:),
21 July 2023, <https://en.wikipedia.org/w/
index.php?title=Anti-pattern&oldid=1144938932>.
Acknowledgments
Julian Reschke opened the author's eyes to the fundamental problem of
restatements, possibly not using this word. Many IETFers over
decades have worked on mitigating restatements; the author apologizes
that examples in this memo naturally mainly come from the author's
own recollection.
Author's Address
Carsten Bormann
Universität Bremen TZI
Postfach 330440
D-28359 Bremen
Germany
Phone: +49-421-218-63921
Email: cabo@tzi.org
Bormann Expires 3 September 2024 [Page 15]
