python-peps/pep-0001.txt

PEP: 1
Title: PEP Purpose and Guidelines
Author: Barry Warsaw, Jeremy Hylton, David Goodger, Nick Coghlan
Status: Active
Type: Process
Content-Type: text/x-rst
Created: 13-Jun-2000
Post-History: 21-Mar-2001, 29-Jul-2002, 03-May-2003, 05-May-2012,
              07-Apr-2013


What is a PEP?
==============

PEP stands for Python Enhancement Proposal.  A PEP is a design
document providing information to the Python community, or describing
a new feature for Python or its processes or environment.  The PEP
should provide a concise technical specification of the feature and a
rationale for the feature.

We intend PEPs to be the primary mechanisms for proposing major new
features, for collecting community input on an issue, and for
documenting the design decisions that have gone into Python.  The PEP
author is responsible for building consensus within the community and
documenting dissenting opinions.

Because the PEPs are maintained as text files in a versioned
repository, their revision history is the historical record of the
feature proposal. This historical record is available by the normal git
commands for retrieving older revisions, and can also be browsed
`on GitHub <https://github.com/python/peps>`__.


PEP Audience
============

The typical primary audience for PEPs are the core developers of the CPython
reference interpreter and their elected Steering Council, as well as developers
of other implementations of the Python language specification.

However, other parts of the Python community may also choose to use the process
(particularly for Informational PEPs) to document expected API conventions and
to manage complex design coordination problems that require collaboration across
multiple projects.


PEP Types
=========

There are three kinds of PEP:

1. A **Standards Track** PEP describes a new feature or implementation
   for Python. It may also describe an interoperability standard that will
   be supported outside the standard library for current Python versions
   before a subsequent PEP adds standard library support in a future
   version.

2. An **Informational** PEP describes a Python design issue, or
   provides general guidelines or information to the Python community,
   but does not propose a new feature.  Informational PEPs do not
   necessarily represent a Python community consensus or
   recommendation, so users and implementers are free to ignore
   Informational PEPs or follow their advice.

3. A **Process** PEP describes a process surrounding Python, or
   proposes a change to (or an event in) a process.  Process PEPs are
   like Standards Track PEPs but apply to areas other than the Python
   language itself.  They may propose an implementation, but not to
   Python's codebase; they often require community consensus; unlike
   Informational PEPs, they are more than recommendations, and users
   are typically not free to ignore them.  Examples include
   procedures, guidelines, changes to the decision-making process, and
   changes to the tools or environment used in Python development.
   Any meta-PEP is also considered a Process PEP.


PEP Workflow
============

Python's Steering Council
-------------------------

There are several references in this PEP to the "Steering Council" or "Council".
This refers to the current members of the elected Steering Council described
in :pep:`13`, in their role as the final authorities on whether or not PEPs
will be accepted or rejected.


Python's Core Developers
------------------------

There are several references in this PEP to "core developers". This refers to
the currently active Python core team members described in :pep:`13`.


Python's BDFL
-------------

Previous versions of this PEP used the title "BDFL-Delegate" for PEP decision
makers. This was a historical reference to Python's previous governance model,
where all design authority ultimately derived from Guido van Rossum, the
original creator of the Python programming language. By contrast, the Steering
Council's design authority derives from their election by the currently active
core developers. Now, PEP-Delegate is used in place of BDFL-Delegate.


PEP Editors
-----------

The PEP editors are individuals responsible for managing the administrative
and editorial aspects of the PEP workflow (e.g. assigning PEP numbers and
changing their status).  See `PEP Editor Responsibilities & Workflow`_ for
details.

PEP editorship is by invitation of the current editors, and they can be
contacted by mentioning ``@python/pep-editors`` on GitHub.  All of the PEP
workflow can be conducted via the GitHub `PEP repository`_ issues and pull
requests.


Start with an idea for Python
-----------------------------

The PEP process begins with a new idea for Python.  It is highly
recommended that a single PEP contain a single key proposal or new
idea; the more focused the PEP, the more successful it tends to be.
Most enhancements and bug fixes don't need a PEP and
can be submitted directly to the `Python issue tracker`_.
The PEP editors reserve the
right to reject PEP proposals if they appear too unfocused or too
broad.  If in doubt, split your PEP into several well-focused ones.

Each PEP must have a champion -- someone who writes the PEP using the style
and format described below, shepherds the discussions in the appropriate
forums, and attempts to build community consensus around the idea.  The PEP
champion (a.k.a. Author) should first attempt to ascertain whether the idea is
PEP-able.  Posting to the `Ideas category`_ of the `Python Discourse`_ is usually
the best way to go about this, unless a more specialized venue is appropriate,
such as `Typing-SIG`_ for static typing or the `Packaging category`_ of the
Python Discourse for packaging issues.

Vetting an idea publicly before going as far as writing a PEP is meant
to save the potential author time. Many ideas have been brought
forward for changing Python that have been rejected for various
reasons. Asking the Python community first if an idea is original
helps prevent too much time being spent on something that is
guaranteed to be rejected based on prior discussions (searching
the internet does not always do the trick). It also helps to make sure
the idea is applicable to the entire community and not just the author.
Just because an idea sounds good to the author does not
mean it will work for most people in most areas where Python is used.

Once the champion has asked the Python community as to whether an
idea has any chance of acceptance, a draft PEP should be presented to
the appropriate venue mentioned above.
This gives the author a chance to flesh out the draft
PEP to make properly formatted, of high quality, and to address
initial concerns about the proposal.


Submitting a PEP
----------------

Following the above initial discussion, the workflow varies based on whether
any of the PEP's co-authors are core developers. If one or more of the PEP's
co-authors are core developers, they are responsible for following the process
outlined below. Otherwise (i.e. none of the co-authors are core developers),
then the PEP author(s) will need to find a sponsor for the PEP.

Ideally, a core developer sponsor is identified, but non-core sponsors may also
be selected with the approval of the Steering Council.  Members of the GitHub
"PEP editors" team are pre-approved to be sponsors.  The sponsor's job is to
provide guidance to the PEP author to help them through the logistics of the
PEP process (somewhat acting like a mentor).  Being a sponsor does **not**
disqualify that person from becoming a co-author or PEP-Delegate later on (but
not both).  The sponsor of a PEP is recorded in the "Sponsor:" field of the
header.

Once the sponsor or the core developer(s) co-authoring the PEP deem the PEP
ready for submission, the proposal should be submitted as a draft PEP via a
`GitHub pull request`_.  The draft must be written in PEP style as described
below, else it will fail review immediately (although minor errors may be
corrected by the editors).

The standard PEP workflow is:

* You, the PEP author, fork the `PEP repository`_, and create a file named
  ``pep-9999.rst`` that contains your new PEP.  Use "9999" as your draft PEP
  number.

* In the "Type:" header field, enter "Standards Track",
  "Informational", or "Process" as appropriate, and for the "Status:"
  field enter "Draft".  For full details, see `PEP Header Preamble`_.

* Update `.github/CODEOWNERS`_ such that any co-author(s) or sponsors
  with write access to the `PEP repository`_ are listed for your new file.
  This ensures any future pull requests changing the file will be assigned
  to them.

* Push this to your GitHub fork and submit a pull request.

* The PEP editors review your PR for structure, formatting, and other
  errors.  For a reST-formatted PEP, :pep:`12` is provided as a template.
  It also provides a complete introduction to reST markup that is used
  in PEPs.  Approval criteria are:

  * It sound and complete.  The ideas must make technical sense.  The
    editors do not consider whether they seem likely to be accepted.
  * The title accurately describes the content.
  * The PEP's language (spelling, grammar, sentence structure, etc.)
    and code style (examples should match :pep:`7` & :pep:`8`) should be
    correct and conformant.  The PEP text will be automatically checked for
    correct reStructuredText formatting when the pull request is submitted.
    PEPs with invalid reST markup will not be approved.

  Editors are generally quite lenient about this initial review,
  expecting that problems will be corrected by the reviewing process.
  **Note:** Approval of the PEP is no guarantee that there are no
  embarrassing mistakes!  Correctness is the responsibility of authors
  and reviewers, not the editors.

  If the PEP isn't ready for approval, an editor will send it back to
  the author for revision, with specific instructions.

* Once approved, they will assign your PEP a number.

Once the review process is complete, and the PEP editors approve it (note that
this is *not* the same as accepting your PEP!), they will squash commit your
pull request onto main.

The PEP editors will not unreasonably deny publication of a PEP.  Reasons for
denying PEP status include duplication of effort, being technically unsound,
not providing proper motivation or addressing backwards compatibility, or not
in keeping with the Python philosophy.  The Steering Council can be consulted
during the approval phase, and are the final arbiter of a draft's PEP-ability.

Developers with write access to the `PEP repository`_ may claim PEP
numbers directly by creating and committing a new PEP. When doing so, the
developer must handle the tasks that would normally be taken care of by the
PEP editors (see `PEP Editor Responsibilities & Workflow`_). This includes
ensuring the initial version meets the expected standards for submitting a
PEP.  Alternately, even developers should submit PEPs via pull request.
When doing so, you are generally expected to handle the process yourself;
if you need assistance from PEP editors, mention ``@python/pep-editors``
on GitHub.

As updates are necessary, the PEP author can check in new versions if they
(or a collaborating developer) have write access to the `PEP repository`_.
Getting a PEP number assigned early can be useful for ease of
reference, especially when multiple draft PEPs are being considered at the
same time.

Standards Track PEPs consist of two parts, a design document and a
reference implementation.  It is generally recommended that at least a
prototype implementation be co-developed with the PEP, as ideas that sound
good in principle sometimes turn out to be impractical when subjected to the
test of implementation.


Discussing a PEP
----------------

As soon as a PEP number has been assigned
and the draft PEP is committed to the `PEP repository`_,
a discussion thread for the PEP should be created
to provide a central place to discuss and review its contents, and the
PEP should be updated so that the ``Discussions-To`` header links to it.

The PEP authors (or sponsor, if applicable) may select any reasonable venue
for the discussion, so long as the the following criteria are met:

* The forum is appropriate to the PEP's topic.
* The thread is publicly available on the web so that all interested parties
  can participate.
* The discussion is subject to the `Python Community Code of Conduct
  <https://www.python.org/psf/conduct/>`_.
* A direct link to the current discussion thread is provided in the PEP
  under the ``Discussions-To`` header.

The `PEPs category`_ of the `Python Discourse`_
is the preferred choice for most new PEPs,
whereas historically the `Python-Dev`_ mailing list was commonly used.
Some specialized topics have specific venues, such as
`Typing-SIG`_ for typing PEPs or the `Packaging category`_ on the Python
Discourse for packaging PEPs. If the PEP authors are unsure of the best venue,
the PEP Sponsor and PEP editors can advise them accordingly.

If a PEP undergoes a significant re-write or other major, substantive
changes to its proposed specification, a new thread should typically be created
in the chosen venue to solicit additional feedback. If this occurs, the
``Discussions-To`` link must be updated and a new ``Post-History`` entry added
pointing to this new thread.

If it is not chosen as the discussion venue,
a brief announcement post should be made to the `PEPs category`_
with at least a link to the rendered PEP and the `Discussions-To` thread
when the draft PEP is committed to the repository
and if a major-enough change is made to trigger a new thread.

PEP authors are responsible for collecting community feedback on a PEP
before submitting it for review. However, to avoid long-winded and
open-ended discussions, strategies such as soliciting private or more
narrowly-tailored feedback in the early design phase,
collaborating with other community members with expertise in the PEP's
subject matter, and picking an appropriately-specialized discussion for the
PEP's topic (if applicable) should be considered.
PEP authors should use their discretion here.

Once the PEP is assigned a number and committed to the PEP repository,
substantive issues should generally be discussed on the canonical public
thread, as opposed to private channels, GitHub pull request reviews or
unrelated venues. This ensures everyone can follow and contribute,
avoids fragmenting the discussion,
and makes sure it is fully considered as part of the PEP review process.
Comments, support, concerns and other feedback on this designated thread
are a critical part of what the Steering Council or PEP-Delegate will
consider when reviewing the PEP.


PEP Review & Resolution
-----------------------

Once the authors have completed a PEP, they may request a review for
style and consistency from the PEP editors.
However, content review and acceptance of the PEP is ultimately the
responsibility of the Steering Council, which is formally initiated by
opening a `Steering Council issue`_ once the authors (and sponsor, if any)
determine the PEP is ready for final review and resolution.

To expedite the process in selected cases (e.g. when a change is clearly
beneficial and ready to be accepted, but the PEP hasn't been formally submitted
for review yet), the Steering Council may also initiate a PEP review, first
notifying the PEP author(s) and giving them a chance to make revisions.

The final authority for PEP approval is the Steering Council. However, whenever
a new PEP is put forward, any core developer who believes they are suitably
experienced to make the final decision on that PEP may offer to serve as its
PEP-Delegate by `notifying the Steering Council <Steering Council issue_>`_
of their intent. If the Steering Council approves their offer,
the PEP-Delegate will then have the authority to approve or reject that PEP.

The term "PEP-Delegate" is used under the Steering Council governance model
for the PEP's designated decision maker,
who is recorded in the "PEP-Delegate" field in the PEP's header.
The term "BDFL-Delegate" is a deprecated alias for PEP-Delegate, a legacy of
the time when when Python was led by `a BDFL <Python's BDFL_>`_.
Any legacy references to "BDFL-Delegate" should be treated as equivalent to
"PEP-Delegate".

An individual offering to nominate themselves as a PEP-Delegate must notify
the relevant authors and (when present) the sponsor for the PEP, and submit
their request to the Steering Council
(which can be done via a `new issue <Steering Council issue_>`_ ).
Those taking on this responsibility are free to seek
additional guidance from the Steering Council at any time, and are also expected
to take the advice and perspectives of other core developers into account.

The Steering Council will generally approve such self-nominations by default,
but may choose to decline them.
Possible reasons for the Steering Council declining a
self-nomination as PEP-Delegate include, but are not limited to, perceptions of
a potential conflict of interest (e.g. working for the same organisation as the
PEP submitter), or simply considering another potential PEP-Delegate to be
more appropriate. If core developers (or other community members) have concerns
regarding the suitability of a PEP-Delegate for any given PEP, they may ask
the Steering Council to review the delegation.

If no volunteer steps forward, then the Steering Council will approach core
developers (and potentially other Python community members) with relevant
expertise, in an attempt to identify a candidate that is willing to serve as
PEP-Delegate for that PEP. If no suitable candidate can be found, then the
PEP will be marked as Deferred until one is available.

Previously appointed PEP-Delegates may choose to step down, or be asked to step
down by the Council, in which case a new PEP-Delegate will be appointed in the
same manner as for a new PEP (including deferral of the PEP if no suitable
replacement can be found). In the event that a PEP-Delegate is asked to step
down, this will overrule any prior acceptance or rejection of the PEP, and it
will revert to Draft status.

When such standing delegations are put in place, the Steering Council will
maintain sufficient public records to allow subsequent Councils, the core
developers, and the wider Python community to understand the delegations that
currently exist, why they were put in place, and the circumstances under which
they may no longer be needed.

For a PEP to be accepted it must meet certain minimum criteria.  It
must be a clear and complete description of the proposed enhancement.
The enhancement must represent a net improvement.  The proposed
implementation, if applicable, must be solid and must not complicate
the interpreter unduly.  Finally, a proposed enhancement must be
"pythonic" in order to be accepted by the Steering Council.  (However,
"pythonic" is an imprecise term; it may be defined as whatever is acceptable to
the Steering Council.  This logic is intentionally circular.)  See :pep:`2`
for standard library module acceptance criteria.

Except where otherwise approved by the Steering Council,
pronouncements of PEP resolution will be posted to the
`PEPs category`_ on the `Python Discourse`_.

Once a PEP has been accepted, the reference implementation must be
completed.  When the reference implementation is complete and incorporated
into the main source code repository, the status will be changed to "Final".

To allow gathering of additional design and interface feedback before committing
to long term stability for a language feature or standard library API, a PEP
may also be marked as "Provisional". This is short for "Provisionally Accepted",
and indicates that the proposal has been accepted for inclusion in the reference
implementation, but additional user feedback is needed before the full design
can be considered "Final". Unlike regular accepted PEPs, provisionally accepted
PEPs may still be Rejected or Withdrawn *even after the related changes have
been included in a Python release*.

Wherever possible, it is considered preferable to reduce the scope of a proposal
to avoid the need to rely on the "Provisional" status (e.g. by deferring some
features to later PEPs), as this status can lead to version compatibility
challenges in the wider Python ecosystem. :pep:`411` provides additional details
on potential use cases for the Provisional status.

A PEP can also be assigned the status "Deferred".  The PEP author or an
editor can assign the PEP this status when no progress is being made
on the PEP.  Once a PEP is deferred, a PEP editor can reassign it
to draft status.

A PEP can also be "Rejected".  Perhaps after all is said and done it
was not a good idea.  It is still important to have a record of this
fact. The "Withdrawn" status is similar - it means that the PEP author
themselves has decided that the PEP is actually a bad idea, or has
accepted that a competing proposal is a better alternative.

When a PEP is Accepted, Rejected or Withdrawn, the PEP should be updated
accordingly. In addition to updating the Status field, at the very least
the Resolution header should be added with a direct link
to the relevant post making a decision on the PEP.

PEPs can also be superseded by a different PEP, rendering the original
obsolete.  This is intended for Informational PEPs, where version 2 of
an API can replace version 1.

The possible paths of the status of PEPs are as follows:

.. image:: pep-0001/process_flow.svg
   :class: invert-in-dark-mode
   :alt: PEP process flow diagram

While not shown in the diagram, "Accepted" PEPs may technically move to
"Rejected" or "Withdrawn" even after acceptance. This will only occur if
the implementation process reveals fundamental flaws in the design that were
not noticed prior to acceptance of the PEP. Unlike Provisional PEPs, these
transitions are only permitted if the accepted proposal has *not* been included
in a Python release - released changes must instead go through the regular
deprecation process (which may require a new PEP providing the rationale for
the deprecation).

Some Informational and Process PEPs may also have a status of "Active"
if they are never meant to be completed.  E.g. :pep:`1` (this PEP).


PEP Maintenance
---------------

In general, PEPs are no longer substantially modified after they have reached
the Accepted, Final, Rejected or Superseded state. Once resolution is reached,
a PEP is considered a historical document rather than a living specification.
Formal documentation of the expected behavior should be maintained elsewhere,
such as the `Language Reference`_ for core features, the `Library Reference`_
for standard library modules or the `PyPA Specifications`_ for packaging.

If changes based on implementation experience and user feedback are made to
Standards track PEPs while in the Provisional or (with SC approval) Accepted
state, they should be noted in the PEP, such that the PEP accurately describes
the implementation at the point where it is marked Final.

Active (Informational and Process) PEPs may be updated over time to reflect
changes to development practices and other details. The precise process
followed in these cases will depend on the nature and purpose of the PEP
in question.

Occasionally, a Deferred or even a Withdrawn PEP may be resurrected
with major updates, but it is often better to just propose a new one.


What belongs in a successful PEP?
=================================

Each PEP should have the following parts/sections:

1. Preamble -- :rfc:`2822` style headers containing meta-data about the
   PEP, including the PEP number, a short descriptive title (limited
   to a maximum of 44 characters), the names, and optionally the
   contact info for each author, etc.

2. Abstract -- a short (~200 word) description of the technical issue
   being addressed.

3. Motivation -- The motivation is critical for PEPs that want to
   change the Python language, library, or ecosystem.  It should
   clearly explain why the existing language specification is
   inadequate to address the problem that the PEP solves.  This can
   include collecting documented support for the PEP from important
   projects in the Python ecosystem.  PEP submissions without
   sufficient motivation may be rejected.

4. Rationale -- The rationale fleshes out the specification by
   describing why particular design decisions were made.  It should
   describe alternate designs that were considered and related work,
   e.g. how the feature is supported in other languages.

   The rationale should provide evidence of consensus within the
   community and discuss important objections or concerns raised
   during discussion.

5. Specification -- The technical specification should describe the
   syntax and semantics of any new language feature.  The
   specification should be detailed enough to allow competing,
   interoperable implementations for at least the current major Python
   platforms (CPython, Jython, IronPython, PyPy).

6. Backwards Compatibility -- All PEPs that introduce backwards
   incompatibilities must include a section describing these
   incompatibilities and their severity.  The PEP must explain how the
   author proposes to deal with these incompatibilities.  PEP
   submissions without a sufficient backwards compatibility treatise
   may be rejected outright.

7. Security Implications -- If there are security concerns in relation
   to the PEP, those concerns should be explicitly written out to make
   sure reviewers of the PEP are aware of them.

8. How to Teach This -- For a PEP that adds new functionality or changes
   language behavior, it is helpful to include a section on how to
   teach users, new and experienced, how to apply the PEP to their
   work.

   This section may include key points and recommended documentation
   changes that would help users adopt a new feature or migrate their
   code to use a language change.

9. Reference Implementation -- The reference implementation must be
   completed before any PEP is given status "Final", but it need not
   be completed before the PEP is accepted.  While there is merit
   to the approach of reaching consensus on the specification and
   rationale before writing code, the principle of "rough consensus
   and running code" is still useful when it comes to resolving many
   discussions of API details.

   The final implementation must include test code and documentation
   appropriate for either the Python language reference or the
   standard library reference.

10. Rejected Ideas -- Throughout the discussion of a PEP, various ideas
    will be proposed which are not accepted. Those rejected ideas should
    be recorded along with the reasoning as to why they were rejected.
    This both helps record the thought process behind the final version
    of the PEP as well as preventing people from bringing up the same
    rejected idea again in subsequent discussions.

    In a way this section can be thought of as a breakout section of the
    Rationale section that is focused specifically on why certain ideas
    were not ultimately pursued.

11. Open Issues -- While a PEP is in draft, ideas can come up which
    warrant further discussion. Those ideas should be recorded so people
    know that they are being thought about but do not have a concrete
    resolution. This helps make sure all issues required for the PEP to be
    ready for consideration are complete and reduces people duplicating
    prior discussion.

12. Footnotes -- A collection of footnotes cited in the PEP, and
    a place to list non-inline hyperlink targets.

13. Copyright/license -- Each new PEP must be placed under a dual license of
    public domain and CC0-1.0-Universal_ (see this PEP for an example).


PEP Formats and Templates
=========================

PEPs are UTF-8 encoded text files using the reStructuredText_ format.
reStructuredText allows for rich markup that is still quite easy to
read, but also results in good-looking and functional HTML. :pep:`12`
contains instructions and a :pep:`PEP template <12#suggested-sections>`.

The PEP text files are automatically
`converted to HTML <https://peps.python.org/docs/rendering_system/>`__
(via a `Sphinx <https://www.sphinx-doc.org/>`_-based :pep:`build system <676>`)
for easier `online reading <https://peps.python.org/>`__.


PEP Header Preamble
===================

Each PEP must begin with an :rfc:`2822` style header preamble.  The headers
must appear in the following order.  Headers marked with "*" are
optional and are described below.  All other headers are required.

.. code-block:: text

    PEP: <pep number>
    Title: <pep title>
    Author: <list of authors' real names and optionally, email addrs>
  * Sponsor: <real name of sponsor>
  * PEP-Delegate: <PEP delegate's real name>
    Discussions-To: <URL of current canonical discussion thread>
    Status: <Draft | Active | Accepted | Provisional | Deferred | Rejected |
             Withdrawn | Final | Superseded>
    Type: <Standards Track | Informational | Process>
  * Topic: <Governance | Packaging | Release | Typing>
  * Content-Type: text/x-rst
  * Requires: <pep numbers>
    Created: <date created on, in dd-mmm-yyyy format>
  * Python-Version: <version number>
    Post-History: <dates, in dd-mmm-yyyy format,
                   inline-linked to PEP discussion threads>
  * Replaces: <pep number>
  * Superseded-By: <pep number>
  * Resolution: <url>

The Author header lists the names, and optionally the email addresses
of all the authors/owners of the PEP.  The format of the Author header
values must be:

.. code-block:: text

    Random J. User <random@example.com>

if the email address is included, and just:

.. code-block:: text

    Random J. User

if the address is not given.

If there are multiple authors, each should be on a separate line
following :rfc:`2822` continuation line conventions.  Note that personal
email addresses in PEPs will be obscured as a defense against spam
harvesters.

The Sponsor field records which developer (core, or otherwise approved by the
Steering Council) is sponsoring the PEP.  If one of the authors of the PEP is a
core developer then no sponsor is necessary and thus this field should be left
out.

The PEP-Delegate field is used to record the individual appointed by the
Steering Council to make the final decision on whether or not to approve or
reject a PEP. (The delegate's email address is currently omitted due to a
limitation in the email address masking for reStructuredText PEPs)

*Note: The Resolution header is required for Standards Track PEPs
only.  It contains a URL that should point to an email message or
other web resource where the pronouncement about
(i.e. approval or rejection of) the PEP is made.*

The Discussions-To header provides the URL to the current
canonical discussion thread for the PEP.
For email lists, this should be a direct link to the thread in the list's
archives, rather than just a mailto: or hyperlink to the list itself.

The Type header specifies the type of PEP: Standards Track,
Informational, or Process.

The optional Topic header lists the special topic, if any,
the PEP belongs under.
See the :ref:`topic-index` for the existing topics.

The format of a PEP is specified with a Content-Type header.
All PEPs must use reStructuredText (see :pep:`12`),
and have a value of ``text/x-rst``, the default.
Previously, plaintext PEPs used ``text/plain`` (see :pep:`9`).

The Created header records the date that the PEP was assigned a
number, while Post-History is used to record the dates of and corresponding
URLs to the Discussions-To threads for the PEP, with the former as the
linked text, and the latter as the link target.
Both sets of dates should be in ``dd-mmm-yyyy`` format, e.g. ``14-Aug-2001``.

Standards Track PEPs will typically have a Python-Version header which
indicates the version of Python that the feature will be released with.
Standards Track PEPs without a Python-Version header indicate
interoperability standards that will initially be supported through
external libraries and tools, and then potentially supplemented by a later PEP
to add support to the standard library. Informational and Process PEPs do
not need a Python-Version header.

PEPs may have a Requires header, indicating the PEP numbers that this
PEP depends on.

PEPs may also have a Superseded-By header indicating that a PEP has
been rendered obsolete by a later document; the value is the number of
the PEP that replaces the current document.  The newer PEP must have a
Replaces header containing the number of the PEP that it rendered
obsolete.


Auxiliary Files
===============

PEPs may include auxiliary files such as diagrams.  Such files should be
named ``pep-XXXX-Y.ext``, where "XXXX" is the PEP number, "Y" is a
serial number (starting at 1), and "ext" is replaced by the actual
file extension (e.g. "png").

Alternatively, all support files may be placed in a subdirectory called
``pep-XXXX``, where "XXXX" is the PEP number. When using a subdirectory, there
are no constraints on the names used in files.


Changing Existing PEPs
======================

Draft PEPs are freely open for discussion and proposed modification, at the
discretion of the authors, until submitted to the Steering Council or
PEP-Delegate for review and resolution. Substantive content changes should
generally be first proposed on the PEP's discussion thread listed in its
``Discussions-To`` header, while copyedits and corrections can be submitted
as a `GitHub issue`_ or `GitHub pull request`_.
PEP authors with write access to the PEP repository can update the PEPs
themselves by using ``git push`` or a GitHub PR to submit their changes.
For guidance on modifying other PEPs, consult the `PEP Maintenance`_ section.

See the `Contributing Guide`_ for additional details, and when in doubt,
please check first with the PEP author and/or a PEP editor.


Transferring PEP Ownership
==========================

It occasionally becomes necessary to transfer ownership of PEPs to a
new champion.  In general, it is preferable to retain the original author as
a co-author of the transferred PEP, but that's really up to the
original author.  A good reason to transfer ownership is because the
original author no longer has the time or interest in updating it or
following through with the PEP process, or has fallen off the face of
the 'net (i.e. is unreachable or not responding to email).  A bad
reason to transfer ownership is because the author doesn't agree with the
direction of the PEP.  One aim of the PEP process is to try to build
consensus around a PEP, but if that's not possible, an author can always
submit a competing PEP.

If you are interested in assuming ownership of a PEP, you can also do this via
pull request.  Fork the `PEP repository`_, make your ownership modification,
and submit a pull request.  You should mention both the original author and
``@python/pep-editors`` in a comment on the pull request.  (If the original
author's GitHub username is unknown, use email.)  If the original author
doesn't respond in a timely manner, the PEP editors will make a
unilateral decision (it's not like such decisions can't be reversed :).


PEP Editor Responsibilities & Workflow
======================================

A PEP editor must be added to the ``@python/pep-editors`` group on GitHub and
must watch the `PEP repository`_.

Note that developers with write access to the `PEP repository`_ may
handle the tasks that would normally be taken care of by the PEP editors.
Alternately, even developers may request assistance from PEP editors by
mentioning ``@python/pep-editors`` on GitHub.

For each new PEP that comes in an editor does the following:

* Make sure that the PEP is either co-authored by a core developer, has a core
  developer as a sponsor, or has a sponsor specifically approved for this PEP
  by the Steering Council.

* Read the PEP to check if it is ready: sound and complete.  The ideas
  must make technical sense, even if they don't seem likely to be
  accepted.

* The title should accurately describe the content.

* The file name extension is correct (i.e. ``.rst``).

* Ensure that everyone listed as a sponsor or co-author of the PEP who has write
  access to the `PEP repository`_ is added to `.github/CODEOWNERS`_.

* Skim the PEP for obvious defects in language (spelling, grammar,
  sentence structure, etc.), and code style (examples should conform to
  :pep:`7` & :pep:`8`).  Editors may correct problems themselves, but are
  not required to do so (reStructuredText syntax is checked by the repo's CI).

* If a project is portrayed as benefiting from or supporting the PEP, make sure
  there is some direct indication from the project included to make the support
  clear. This is to avoid a PEP accidentally portraying a project as supporting
  a PEP when in fact the support is based on conjecture.

If the PEP isn't ready, an editor will send it back to the author for
revision, with specific instructions.  If reST formatting is a
problem, ask the author(s) to use :pep:`12` as a template and resubmit.

Once the PEP is ready for the repository, a PEP editor will:

* Assign a PEP number (almost always just the next available number,
  but sometimes it's a special/joke number, like 666 or 3141).
  (Clarification: For Python 3, numbers in the 3000s were used for
  Py3k-specific proposals.  But now that all new features go into
  Python 3 only, the process is back to using numbers in the 100s again.
  Remember that numbers below 100 are meta-PEPs.)

* Check that the author has correctly labeled the PEP's type
  ("Standards Track", "Informational", or "Process"), and marked its
  status as "Draft".

* Ensure all CI build and lint checks pass without errors,
  and there are no obvious issues in the rendered preview output.

* Merge the new (or updated) PEP.

* Inform the author of the next steps (open a discussion thread and
  update the PEP with it, post an announcement, etc).

Updates to existing PEPs should be submitted as a `GitHub pull request`_.

Many PEPs are written and maintained by developers with write access
to the Python codebase.  The PEP editors monitor the PEP repository
for changes, and correct any structure, grammar, spelling, or
markup mistakes they see.

PEP editors don't pass judgment on PEPs.  They merely do the
administrative & editorial part (which is generally a low volume task).

Resources:

* `Index of Python Enhancement Proposals <https://peps.python.org/>`_

* `Following Python's Development
  <https://devguide.python.org/communication/>`_

* `Python Developer's Guide <https://devguide.python.org/>`_


Footnotes
=========

.. _.github/CODEOWNERS: https://docs.github.com/en/repositories/managing-your-repositorys-settings-and-features/customizing-your-repository/about-code-owners

.. _Python issue tracker: https://github.com/python/cpython/issues

.. _CC0-1.0-Universal: https://choosealicense.com/licenses/cc0-1.0/

.. _reStructuredText: https://www.sphinx-doc.org/en/master/usage/restructuredtext/index.html

.. _PEP repository: https://github.com/python/peps

.. _GitHub pull request: https://github.com/python/peps/pulls

.. _GitHub issue: https://github.com/python/peps/issues

.. _Steering Council issue: https://github.com/python/steering-council/issues/new/choose

.. _Python-Dev: https://mail.python.org/mailman3/lists/python-dev.python.org/

.. _Python Discourse: https://discuss.python.org/

.. _Ideas category: https://discuss.python.org/c/ideas/

.. _PEPs category: https://discuss.python.org/c/peps/

.. _Typing-SIG: https://mail.python.org/mailman3/lists/typing-sig.python.org/

.. _Packaging category: https://discuss.python.org/c/packaging/

.. _Language Reference: https://docs.python.org/3/reference/index.html

.. _Library Reference: https://docs.python.org/3/library/index.html

.. _PyPA Specifications: https://packaging.python.org/en/latest/specifications/

.. _Contributing Guide: https://github.com/python/peps/blob/main/CONTRIBUTING.rst


Copyright
=========

This document is placed in the public domain or under the
CC0-1.0-Universal license, whichever is more permissive.


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