zip-0000.rst

::

  ZIP: 0
  Title: ZIP Process
  Owners: Daira Emma Hopwood <daira@electriccoin.co>
          teor <teor@zfnd.org>
          Jack Grigg <str4d@electriccoin.co>
          Conrado Gouvea <conrado@zfnd.org>
          Aditya Bharadwaj <nighthawk24@gmail.com>
          Arya <arya@zfnd.org>
  Original-Authors: Daira Emma Hopwood
                    Josh Cincinnati
                    George Tankersley
                    Deirdre Connolly
  Credits: Luke Dashjr
  Status: Active
  Category: Process
  Created: 2019-02-16
  License: BSD-2-Clause



Terminology
===========

The key words "MUST", "MUST NOT", "SHOULD", "SHOULD NOT", "MAY",
"RECOMMENDED", "OPTIONAL", and "REQUIRED" in this document are to
be interpreted as described in BCP 14 [#BCP14]_ when, and only when,
they appear in all capitals.

The term "network upgrade" in this document is to be interpreted as
described in ZIP 200. [#zip-0200]_


Abstract
========

A Zcash Improvement Proposal (ZIP) is a design document providing
information to the Zcash community, or describing a new feature for
Zcash or its processes or environment. The ZIP should provide a concise
technical specification of the feature and a rationale for the feature.

We intend ZIPs to be the primary mechanism for proposing new features,
for collecting community input on an issue, and for documenting the
design decisions that have gone into Zcash. The Owner(s) of the ZIP
(usually the authors(s)) are responsible for building consensus within
the community and documenting dissenting opinions.

Because the ZIPs are maintained as text files in a versioned repository,
their revision history is the historical record of the feature proposal.

This document is based partly on the work done by Luke Dashjr with
`BIP 2 <https://github.com/bitcoin/bips/blob/master/bip-0002.mediawiki>`__.


ZIP Workflow
============

The ZIP process begins with a new idea for Zcash. Each potential ZIP
must have Owners — one or more people who write the ZIP using the style
and format described below, shepherd the discussions in the appropriate
forums, and attempt to build community consensus around the idea. The
ZIP Owners should first attempt to ascertain whether the idea is ZIP-able.
Small enhancements or patches to a particular piece of software often
don't require standardisation between multiple projects; these don't
need a ZIP and should be injected into the relevant project-specific
development workflow with a patch submission to the applicable issue
tracker. Additionally, many ideas have been brought forward for changing
Zcash that have been rejected for various reasons. The first step should
be to search past discussions to see if an idea has been considered
before, and if so, what issues arose in its progression. After
investigating past work, the best way to proceed is by posting about the
new idea to the `Zcash Community Forum <https://forum.zcashcommunity.com/>`__.

Vetting an idea publicly before going as far as writing a ZIP is meant
to save both the potential Owners and the wider community time. Asking
the Zcash 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 Owners. Just because an idea sounds good to
the Owners does not mean it will work for most people in most areas
where Zcash is used.

Once the Owners have asked the Zcash community as to whether an idea
has any chance of acceptance, a draft ZIP should be presented to the
`Zcash Community Forum <https://forum.zcashcommunity.com/>`__.
This gives the Owners a chance to flesh out the draft ZIP to make it
properly formatted, of high quality, and to address additional concerns
about the proposal. Following a discussion, the proposal should be
submitted to the ZIPs git repository [#zips-repo]_ as a pull request.
This draft must be written in ZIP style as described below, and named
with an alias such as ``draft-zatoshizakamoto-42millionzec`` until the
ZIP Editors have assigned it a ZIP number (Owners MUST NOT self-assign
ZIP numbers).

ZIP Owners are responsible for collecting community feedback on both
the initial idea and the ZIP before submitting it for review. However,
wherever possible, long open-ended discussions on forums should be avoided.

It is highly recommended that a single ZIP contain a single key proposal
or new idea. The more focused the ZIP, the more successful it tends to
be. If in doubt, split your ZIP into several well-focused ones.

When the ZIP draft is complete, the ZIP Editors will assign the ZIP a
number (if that has not already been done) and one or more Categories,
and merge the pull request to the ZIPs git repository. The ZIP Editors
will not unreasonably reject a ZIP. Reasons for rejecting ZIPs include
duplication of effort, disregard for formatting rules, being too
unfocused or too broad, being technically unsound, not providing proper
motivation or not in keeping with the Zcash philosophy. For a ZIP 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 protocol unduly.

The ZIP Owners may update the draft as necessary in the git repository.
Updates to drafts should also be submitted by the Owners as pull requests.


ZIP Numbering Conventions
-------------------------

The ZIP Editors currently use the following conventions when numbering
ZIPs:

* if a ZIP directly corresponds to a BIP (Bitcoin Improvement Proposal),
  and the number doesn't clash, assign the same number;
* if it affects the consensus layer or the core protocol, assign a
  number in the range 200..299;
* if it affects only higher layers but is needed for interoperability
  between node implementations or other parts of the ecosystem, assign
  a number in the range 300..399;
* if it is specific to an implementation (e.g. zcashd or zebra), assign
  a number in the range 400..499;
* if it concerns Consensus Process, assign a number in the range 0..9
  or above 1000;
* try to number ZIPs that should or will be deployed together
  consecutively (subject to the above conventions), and in a coherent
  reading order.

These conventions are subject to change by consensus of the ZIP Editors.


Transferring ZIP Ownership
--------------------------

It occasionally becomes necessary to transfer ownership of ZIPs to a new
Owner. In general, we'd like to retain the original Owner as a
co-Owner of the transferred ZIP, but that's really up to the original
Owner. A good reason to transfer ownership is because the original
Owner no longer has the time or interest in updating it or following
through with the ZIP 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 you don't agree with the direction of the
ZIP. We try to build consensus around a ZIP, but if that's not possible,
you can always submit a competing ZIP.

If you are interested in assuming ownership of a ZIP, send a message
asking to take over, addressed to all of the current Owner(s) and the
ZIP Editors. If the Owner(s) who are proposed to be removed don't respond
in a timely manner, the ZIP Editors and any remaining current Owners will
make a decision (such decisions may be reversed).

If an author of a ZIP is no longer an Owner, an Original-Authors: field
SHOULD be added to the ZIP metadata indicating the original authorship
(without email addresses), unless the original author(s) request otherwise.


ZIP Editors
-----------

The current ZIP Editors are:

* Daira Emma Hopwood and Jack Grigg, associated with the Electric Coin
  Company;
* teor, Conrado Gouvea, and Arya, associated with the Zcash Foundation.
* Aditya Bharadwaj, associated with Nighthawk Apps.

All can be reached at zips@z.cash. The current design of the ZIP Process
dictates that there are always at least two ZIP Editors: at least one
from the Electric Coin Company and at least one from the Zcash Foundation.

ZIP Editors MUST declare any potential or perceived conflict of interest
they have relating to their responsibilities as ZIP Editors.

ZIP Editors MUST be publicly transparent about any external influence
or constraints that have been placed or attempted to be placed on their
actions as ZIP Editors (including from the Electric Coin Company,
Zcash Foundation, or Nighthawk Apps), whether or not it affects those
actions. This should not be interpreted as requiring ZIP Editors to
reveal knowledge of undisclosed security vulnerabilities or mitigations.

Additional Editors may be selected, with their consent, by consensus
among the current Editors.

An Editor may be removed or replaced by consensus among the current
Editors. However, if the other ZIP Editors have consensus, an Editor
can not prevent their own removal.

Any Editor can resign by informing the other Editors in writing.

Whenever the ZIP Editors change, the new ZIP Editors SHOULD:

* review this ZIP to make sure it reflects current practice,
* update the Owners of this ZIP,
* review access to the `ZIPs repository <https://github.com/zcash/zips>`_,
* update the <zips@z.cash> email alias, and
* invite new Editors to the Zcash Community Forum, and the #zips channel on Discord.

If it has been at least 12 months since the last ZIP Editor change, the ZIP Editors SHOULD:

* review this ZIP to make sure it reflects current practice.


ZIP Editor Responsibilities
---------------------------

The ZIP Editors subscribe to the `Zcash Community Forum.
<https://forum.zcashcommunity.com/>`__

Each new ZIP SHOULD be submitted as a "pull request" to the ZIPs git
repository [#zips-repo]_. It SHOULD NOT contain a ZIP number unless
one had already been assigned by the ZIP Editors. The pull request
SHOULD initially be marked as a Draft. The ZIP content SHOULD be
submitted in reStructuredText [#rst]_ or Markdown [#markdown]_
format. Generating HTML for a ZIP is OPTIONAL.

For each new ZIP that comes in, the ZIP Editors SHOULD:

* Read the ZIP 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.
* Check that the title accurately describes the content.
* Ensure that the ZIP draft has been sent to the Zcash Community Forum
  and as a PR to the ZIPs git repository [#zips-repo]_.
* Ensure that motivation and backward compatibility have been
  addressed, if applicable.
* Check that the licensing terms are acceptable for ZIPs.

Reviewing a ZIP
---------------

Any ZIP Editor can suggest changes to a ZIP. These suggestions are the
opinion of the individual ZIP Editor. Any technical or process review that
ZIP Editors perform is expected to be independent of their contractual or
other relationships.

ZIP Owners are free to clarify, modify, or decline suggestions from ZIP Editors.
If the ZIP Editors make a change to a ZIP that the Owners disagree with, then
the Editors SHOULD revert the change.


Typically, the ZIP Editors suggest changes in two phases:

* `content review`: multiple ZIP Editors discuss the ZIP, and suggest
  changes to the overall content. This is a "big picture" review.
* `format review`: two ZIP Editors do a detailed review of the
  structure and format of the ZIP. This ensures the ZIP is consistent
  with other Zcash specifications.

If the ZIP isn't ready, the Editors will send it back to the Owners for
revision, with specific instructions. This decision is made by consensus
among the current Editors.

When a ZIP is ready, the ZIP Editors will:

* Ensure that a unique ZIP number has been assigned in the pull request.
* Regenerate the corresponding HTML documents, if required.
* Remove Draft status and merge the pull request.

The ZIP editors monitor ZIP changes and update ZIP headers as
appropriate.

Rejecting a ZIP or update
-------------------------

The ZIP Editors MAY reject a new ZIP or an update to an existing ZIP,
by consensus among the current Editors. Rejections can be based on any
of the following reasons:

* it violates the Zcash Code of Conduct [#conduct]_ ;
* it appears too unfocused or broad;
* it duplicates effort in other ZIPs without sufficient technical justification
  (however, alternative proposals to address similar or overlapping problems
  are not excluded for this reason);
* it has manifest security flaws (including being unrealistically dependent
  on user vigilance to avoid security weaknesses);
* it disregards compatibility with the existing Zcash blockchain or ecosystem;
* it is manifestly unimplementable;
* it includes buggy code, pseudocode, or algorithms;
* it manifestly violates common expectations of a significant portion of the
  Zcash community;
* it updates a ZIP's status, or fails to make a needed status update, in a way
  inconsistent with the requirements in `Specification of Status Workflow`_;
* in the case of a Proposed, Active, Implemented, or Final ZIP, the update
  makes a substantive change to which there is significant community opposition;
* it is dependent on a patent that could potentially be an obstacle to
  adoption of the ZIP;
* it includes commercial advertising or spam;
* it disregards formatting rules;
* it makes non-editorial edits to previous entries in a ZIP's Change history,
  if there is one;
* an update to an existing ZIP extends or changes its scope to an extent
  that would be better handled as a separate ZIP;
* a new ZIP has a category that does not reflect its content, or an update
  would change a ZIP to an inappropriate category;
* it violates any specific "MUST" or "MUST NOT" rule in this document;
* the expressed political views of a Owner of the document are inimical
  to the Zcash Code of Conduct [#conduct]_ (except in the case of an update
  removing that Owner);
* it is not authorized by the stated ZIP Owners;
* it removes an Owner without their consent (unless the reason for removal
  is directly related to a breach of the Code of Conduct by that Owner);
* it violates a conformance requirement of any Active Process ZIP
  (including this ZIP).

The ZIP Editors MUST NOT unreasonably deny publication of a ZIP proposal
or update that does not violate any of these criteria. If they refuse a
proposal or update, they MUST give an explanation of which of the
criteria were violated, with the exception that spam may be deleted
without an explanation.

Note that it is not the primary responsibility of the ZIP Editors to
review proposals for security, correctness, or implementability.

Communicating with the ZIP Editors
----------------------------------

Please send all ZIP-related communications either:

* by email to <zips@z.cash>,
* by opening an issue on the `ZIPs issue tracker <https://github.com/zcash/zips/issues>`_, or
* by sending a message in the `#zips channel on the Zcash R&D Discord <https://discord.com/channels/809218587167293450/809251050741170187>`_.

**All communications should abide by the Zcash Code of Conduct** [#conduct]_
**and follow the GNU Kind Communication Guidelines** [#gnukind]_.

ZIP Editor Meeting Practices
----------------------------

The ZIP Editors SHOULD meet on a regular basis to review draft changes to
ZIPs. Meeting times are agreed by consensus among the current ZIP Editors.
A ZIP Editor meeting can be held even if some ZIP Editors are not available, but
all Editors SHOULD be informed of significant decisions that are likely to be made
at upcoming meetings.

The ZIP Editors will appoint a ZIP Secretary, which can be a shared or rotating
role. The ZIP Secretary will:

* share a draft agenda with the ZIP Editors at least 24 hours before each ZIP Editors' meeting;
* share draft minutes of significant decisions with the ZIP Editors in the week after the
  ZIP Editors' meeting; and
* share significant ZIP changes, including significant changes of status (in
  particular, progression of a ZIP to Proposed status), on the Zcash Community
  Forum.

If the draft agenda is empty, any ZIP Editor MAY submit agenda items, or suggest
that the meeting is cancelled.

ZIP format and structure
========================

ZIPs SHOULD be written in reStructuredText [#rst]_, Markdown [#markdown]_,
or LaTeX [#latex]_. For ZIPs written in LaTeX, a ``Makefile`` MUST be
provided to build (at least) a PDF version of the document.

Each ZIP SHOULD have the following parts:

* Preamble — Headers containing metadata about the ZIP (`see
  below <#zip-header-preamble>`__).
  The License field of the preamble indicates the licensing terms,
  which MUST be acceptable according to `the ZIP licensing requirements <#zip-licensing>`__.

* Terminology — Definitions of technical or non-obvious terms used
  in the document.

* Abstract — A short (~200 word) description of the technical issue
  being addressed.

* Motivation — The motivation is critical for ZIPs that want to change
  the Zcash protocol. It should clearly explain why the existing
  protocol is inadequate to address the problem that the ZIP solves.

* Specification — The technical specification should describe the
  interface and semantics of any new feature. The specification should be
  detailed enough to allow competing, interoperable implementations for
  any of the current Zcash platforms.

* Rationale — The rationale fleshes out the specification by
  describing what motivated the design and why particular design
  decisions were made. It should describe alternate designs that were
  considered and related work. The rationale should provide evidence of
  consensus within the community and discuss important objections or
  concerns raised during discussion.

  For longer ZIPs it can potentially be easier to have inline Rationale
  subsections interspersed throughout the Specification part. When taking
  this approach, the content of these subsections should be annotated
  with HTML tags to make it collapsible (so the rationale is available
  for review but doesn't get in the way of reading the specification).
  ZIPs written in Markdown can use the following syntax (note the
  newline after the ``<summary>`` tag)::

    # Specification

    ## Foobar

    Important details.

    <details>
    <summary>

    ### Rationale for foobar
    </summary>

    Important but hidden rationale!
    </details>

  ZIPs written in reStructuredText can use the following syntax::

    Specification
    =============

    Foobar
    ------

    Important details.

    Rationale for foobar
    ''''''''''''''''''''

    .. raw:: html

       <details>
       <summary>Click to show/hide</summary>

    Important but hidden rationale!

    .. raw:: html

       </details>

* Security and privacy considerations — If applicable, security
  and privacy considerations should be explicitly described, particularly
  if the ZIP makes explicit trade-offs or assumptions. For guidance on
  this section consider RFC 3552 [#RFC3552]_ as a starting point.

* Reference implementation — Literal code implementing the ZIP's
  specification, and/or a link to the reference implementation of
  the ZIP's specification. The reference implementation MUST be
  completed before any ZIP is given status “Implemented” or “Final”,
  but it generally need not be completed before the ZIP is accepted
  into “Proposed”.

ZIP stubs
---------

A ZIP stub records that the ZIP Editors have reserved a number for a
ZIP that is under development. It is not a ZIP, but exists in the ZIPs
git repository [#zips-repo]_ at the same path that will be used for the
corresponding ZIP if and when it is published. It consists only of a
preamble, which MUST use Reserved as the value of the Status field.

ZIP stubs can be added and removed, or replaced by the corresponding ZIP,
at the discretion of the ZIP Editors. If a ZIP stub is removed then its
number MAY be reused, possibly for an entirely different ZIP.

ZIP header preamble
-------------------

Each ZIP or ZIP stub MUST begin with a RFC 822-style header preamble.
For ZIPs and ZIP stubs written in reStructuredText, this is represented
as ``::`` on the first line, followed by a blank line, then the preamble
indented by 2 spaces.

The following header fields are REQUIRED for ZIPs::

  ZIP:
  Title:
  Owners:
  Status:
  Category:
  Created:
  License:

The following additional header fields are OPTIONAL for ZIPs::

  Credits:
  Original-Authors:
  Discussions-To:
  Pull-Request:
  Obsoleted-By:
  Updated-By:
  Obsoletes:
  Updates:

For ZIP stubs, only the ZIP:, Title:, Status:, and Category: fields
are REQUIRED. Typically the other fields applicable to ZIP stubs are
Credits:, Discussions-To: and Pull-Request:, which are OPTIONAL.

The Owners header lists the names and email addresses of all the
Owners of the ZIP. The format of the Owners header value SHOULD be::

  Random J. User <address@dom.ain>

If there are multiple Owners, each should be on a separate line.

Credits: and Original-Authors: fields SHOULD NOT include email addresses.

The "Owners", "Credits", and "Original-Authors" headers always use
these plural spellings even there is only one Owner, one person to be
credited, or one original author.

While a ZIP is in public discussions (usually during the initial Draft
phase), a Discussions-To header will indicate the URL where the ZIP is
being discussed. No Discussions-To header is necessary if the ZIP is being
discussed privately with the Owner.

The Pull-Request header, if present, gives an URL to a Pull Request for
the ZIP.

The Category header specifies the type of ZIP, as described in
`ZIP categories`_. Multiple categories MAY be specified, separated by
" ``/`` ".

The Created header records the date that the ZIP was submitted.
Dates should be in yyyy-mm-dd format, e.g. 2001-08-14.

For ZIPs written in reStructuredText, URLs in header fields SHOULD be
surrounded by ``<`` ``>``; this ensures that the link is rendered correctly.

Auxiliary Files
---------------

ZIPs may include auxiliary files such as diagrams. Auxiliary files
should be included in a subdirectory for that ZIP; that is, for any ZIP
that requires more than one file, all of the files SHOULD be in a
subdirectory named zip-XXXX.


ZIP categories
==============

Each ZIP is in one or more of the following categories, as specified
in the Category header:

Consensus
   Rules that affect the consensus protocol followed by all Zcash
   implementations.
Standards
   Non-consensus changes affecting most or all Zcash implementations, or
   the interoperability of applications using Zcash.
Process
   A Process ZIP describes a process surrounding Zcash, or proposes a
   change to (or an event in) a process. They may propose an implementation,
   but not to Zcash's codebase; they often require community consensus;
   unlike Informational ZIPs, 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 Zcash development.
Consensus Process
   A subcategory of Process ZIP that specifies requirements and processes
   that are to be realized by one or more Consensus ZIPs, and/or by social
   consensus of the Zcash community.
Informational
   An Informational ZIP describes non-consensus Zcash design issues, or
   general guidelines or information for the Zcash community. These ZIPs
   do not necessarily represent a Zcash community consensus or
   recommendation, so users and implementors are free to ignore
   Informational ZIPs or follow their advice.
Network
   Specifications of peer-to-peer networking behaviour.
RPC
   Specifications of the RPC interface provided by zcashd nodes.
Wallet
   Specifications affecting wallets (e.g. non-consensus changes to how
   transactions, addresses, etc. are constructed or interpreted).
Ecosystem
   Specifications otherwise useful to the Zcash ecosystem.

New categories may be added by consensus among the ZIP Editors.

Consensus and Standards ZIPs SHOULD have a Reference Implementation section,
which includes or (more often) links to an implementation.

Consensus ZIPs SHOULD have a Deployment section, describing how and when
the consensus change is planned to be deployed (for example, in a particular
network upgrade).


ZIP Status Field
================

* Reserved: The ZIP Editors have reserved this ZIP number, and there MAY
  be a Pull Request for it, but no ZIP has been published. The ZIP Editors
  SHOULD publish a stub header so that the reservation appears in the
  `ZIP index <https://zips.z.cash#index-of-zips>`__. This status MUST
  only be used for ZIP stubs.

* Draft: All initial ZIP submissions have this status.

* Withdrawn: The Owners of a ZIP MAY remove it from consideration by
  the community, by changing its status to Withdrawn (in a PR or by
  request to the ZIP Editors).

* Active: Typically only used for Process or Informational ZIPs, achieved
  once rough consensus on a Proposed ZIP is reached in PR/forum posts.

* Proposed: Typically the stage after Draft, added to a ZIP after
  consideration, feedback, and rough consensus from the community.

* Rejected: If no progress on a Draft or Proposed ZIP has been made for
  one year, the ZIP Editors SHOULD move it to Rejected status. It can
  revert back to Draft or Proposed if the Owners resume work or resolve
  issues preventing consensus.

* Implemented: When a Consensus or Standards ZIP has a working
  reference implementation but before activation on the Zcash network.
  The status MAY indicate which node implementation has implemented
  the ZIP, e.g. "Implemented (zcashd)" or "Implemented (zebra)".

* Final: When a Consensus or Standards ZIP is both implemented and
  activated on the Zcash network.

* Obsolete: The status when a ZIP is no longer relevant (typically when
  superseded by another ZIP).

Specification of Status Workflow
--------------------------------

Owners of a ZIP MAY decide on their own to change the status between
Draft or Withdrawn. All other changes in status MUST be approved by
consensus among the current ZIP Editors.

A ZIP SHOULD only change status from Draft (or Rejected) to Proposed,
when the Owner deems it is complete and there is rough consensus on the
forums, validated by consensus among the current ZIP Editors. If it's a
Consensus ZIP, a Deployment section MUST be present in order for the ZIP
to change status to Proposed. Typically, although not necessarily, this
will specify a network upgrade in which the consensus change is to activate.

A ZIP's status is Released if it is Proposed, Active, Implemented, or Final
(i.e. not Draft, Rejected, Obsolete, or Withdrawn).

A ZIP SHOULD NOT be changed from a non-Released status to a Released
status if there is significant community opposition to its content.
(However, Draft ZIPs explicitly MAY describe proposals to which there
is, or could be expected, significant community opposition.)

A Released ZIP MUST NOT be changed to a non-Released status if the
specification is already implemented and is in common use, or where a
Process ZIP still reflects a consensus of the community.

A Standards ZIP SHOULD only change status from Proposed to Implemented
once the Owners provide an associated reference implementation. For
Consensus ZIPs, an implementation MUST have been merged into at least
one consensus node codebase (currently zcashd and/or zebra), typically
in the period after the network upgrade's specification freeze but before
the implementation audit. If the Owners miss this deadline, the Editors
or Owners MAY choose to update the Deployment section of the ZIP to
target another upgrade, at their discretion.

A Process or Informational ZIP SHOULD change status from Proposed to
Active when it achieves rough consensus on the forum or PR. Such a
proposal is said to have rough consensus if it has been substantially
complete and open to discussion on the forum or GitHub PR for at least
one month, has been in Proposed status for at least one week, and no
person maintains any unaddressed substantiated objections to it. Addressed
or obstructive objections can be ignored/overruled by general agreement
that they have been sufficiently addressed, but clear reasoning MUST be
given in such circumstances.

When an Active, Implemented, or Final ZIP is no longer relevant –for
example because its implementation has fallen out of use or its process
is no longer followed– its status SHOULD be changed to Obsolete. This
change MUST also be objectively verifiable and/or discussed. Final ZIPs
MAY be updated; the specification is still in force but modified by
another specified ZIP or ZIPs (check the optional Updated-By header).

If a non-editorial update is made to an Obsolete, Withdrawn, or
Rejected ZIP, its status MUST be changed appropriately.


ZIP Comments
============

Comments from the community on the ZIP should occur on the Zcash
Community Forum and the comment fields of the pull requests in
any open ZIPs. Editors will use these sources to judge rough consensus.


ZIP Licensing
=============

New ZIPs may be accepted with the following licenses. Each new ZIP MUST
identify at least one acceptable license in its preamble. Each license
MUST be referenced by their respective abbreviation given below.

For example, a preamble might include the following License header::

  License: BSD-2-Clause
           GNU-All-Permissive

In this case, the ZIP text is fully licensed under both the OSI-approved
BSD 2-clause license as well as the GNU All-Permissive License, and
anyone may modify and redistribute the text provided they comply with
the terms of *either* license. In other words, the license list is an
"OR choice", not an "AND also" requirement.

It is also possible to license source code differently from the ZIP
text. This case SHOULD be indicated in the Reference Implementation
section of the ZIP. Again, each license MUST be referenced by its
respective abbreviation given below.

Statements of code licenses in ZIPs are only advisory; anyone intending
to use the code should look for license statements in the code itself.

ZIPs are not required to be *exclusively* licensed under approved
terms, and MAY also be licensed under unacceptable licenses
*in addition to* at least one acceptable license. In this case, only the
acceptable license(s) should be listed in the License header.


Recommended licenses
--------------------

* MIT: `Expat/MIT/X11 license <https://opensource.org/licenses/MIT>`__
* BSD-2-Clause: `OSI-approved BSD 2-clause
  license <https://opensource.org/licenses/BSD-2-Clause>`__
* BSD-3-Clause: `OSI-approved BSD 3-clause
  license <https://opensource.org/licenses/BSD-3-Clause>`__
* CC0-1.0: `Creative Commons CC0 1.0
  Universal <https://creativecommons.org/publicdomain/zero/1.0/>`__
* GNU-All-Permissive: `GNU All-Permissive
  License <https://www.gnu.org/prep/maintain/html_node/License-Notices-for-Other-Files.html>`__
* Apache-2.0: `Apache License, version
  2.0 <https://www.apache.org/licenses/LICENSE-2.0>`__

In addition, it is RECOMMENDED that literal code included in the ZIP be
dual-licensed under the same license terms as the project it modifies.
For example, literal code intended for zcashd would ideally be
dual-licensed under the MIT license terms as well as one of the above
with the rest of the ZIP text.

Not recommended, but acceptable licenses
----------------------------------------

* BSL-1.0: `Boost Software License, version
  1.0 <https://www.boost.org/LICENSE_1_0.txt>`__
* CC-BY-4.0: `Creative Commons Attribution 4.0
  International <https://creativecommons.org/licenses/by/4.0/>`__
* CC-BY-SA-4.0: `Creative Commons Attribution-ShareAlike 4.0
  International <https://creativecommons.org/licenses/by-sa/4.0/>`__
* AGPL-3.0+: `GNU Affero General Public License (AGPL), version 3 or
  newer <https://www.gnu.org/licenses/agpl-3.0.en.html>`__
* FDL-1.3: `GNU Free Documentation License, version
  1.3 <https://www.gnu.org/licenses/fdl-1.3.en.html>`__
* GPL-2.0+: `GNU General Public License (GPL), version 2 or
  newer <https://www.gnu.org/licenses/old-licenses/gpl-2.0.en.html>`__
* LGPL-2.1+: `GNU Lesser General Public License (LGPL), version 2.1 or
  newer <https://www.gnu.org/licenses/old-licenses/lgpl-2.1.en.html>`__

Not acceptable licenses
-----------------------

All licenses not explicitly included in the above lists are not
acceptable terms and MUST NOT be used for a Zcash Improvement Proposal.

Rationale
---------

Bitcoin's BIP 1 allowed the Open Publication License or releasing into
the public domain; was this insufficient?

* The OPL is generally regarded as obsolete, and not a license suitable
  for new publications.
* The OPL license terms allowed for the author to prevent publication
  and derived works, which was widely considered inappropriate.
* In some jurisdictions, releasing a work to the public domain is not
  recognised as a legitimate legal action, leaving the ZIP simply
  copyrighted with no redistribution or modification allowed at all.

Why are there software licenses included?

* Some ZIPs, especially in the Consensus category, may include literal
  code in the ZIP itself which may not be available under the exact
  license terms of the ZIP.
* Despite this, not all software licenses would be acceptable for
  content included in ZIPs.


See Also
========

* `RFC 7282: On Consensus and Humming in the
  IETF <https://www.rfc-editor.org/rfc/rfc7282.html>`__
* `Zcash Network Upgrade Pipeline <https://electriccoin.co/blog/the-zcash-network-upgrade-pipeline/>`__


References
==========

.. [#BCP14] `Information on BCP 14 — "RFC 2119: Key words for use in RFCs to Indicate Requirement Levels" and "RFC 8174: Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words" <https://www.rfc-editor.org/info/bcp14>`_
.. [#RFC3552] `RFC 3552: Guidelines for Writing RFC Text on Security Considerations <https://www.rfc-editor.org/rfc/rfc3552.html>`_
.. [#zip-0200] `ZIP 200: Network Upgrade Mechanism <zip-0200.rst>`_
.. [#conduct] `Zcash Code of Conduct <https://github.com/zcash/zcash/blob/master/code_of_conduct.md>`_
.. [#gnukind] `GNU Kind Communication Guidelines <https://www.gnu.org/philosophy/kind-communication.en.html>`_
.. [#rst] `reStructuredText documentation <https://docutils.sourceforge.io/rst.html>`_
.. [#markdown] `The Markdown Guide <https://www.markdownguide.org/>`_
.. [#latex] `LaTeX — a document preparation system <https://www.latex-project.org/>`_
.. [#zips-repo] `ZIPs git repository <https://github.com/zcash/zips>`_