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ZIP: 0
Title: ZIP Process
Owners: Daira Hopwood
        Josh Cincinnati
Status: Active
Category: Process
Created: 2019-02-16
License: BSD-2-Clause

Terminology

The key words "MUST", "SHOULD", "SHOULD NOT", "MAY", "RECOMMENDED", "OPTIONAL", and "REQUIRED" in this document are to be interpreted as described in RFC 2119. [1]

The term "network upgrade" in this document is to be interpreted as described in ZIP 200. [2]

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 author(s) of the ZIP (known as Owners in this document) 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 on the work done by Luke Dashjr with BIP 2 and Daira Hopwood with Draft ZIP 0.

ZIP Workflow

The ZIP process begins with a new idea for Zcash. Each potential ZIP must have a Owner -- someone who writes the ZIP using the style and format described below, shepherds the discussions in the appropriate forums, and attempts to build community consensus around the idea. The ZIP Owner (a.k.a. author) 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.

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

Once the Owner has 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. This gives the Owner 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 as a pull request. This draft must be written in ZIP style as described below, and named with an alias such as zip-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, label it as Standards Track, Informational, or Process, 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 Owner may update the draft as necessary in the git repository. Updates to drafts should also be submitted by the Owner as pull requests.

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 both the original Owner and the ZIP Editors. If the original Owner doesn't respond to email in a timely manner, the ZIP Editors will make a unilateral decision (it's not like such decisions can't be reversed :).

ZIP Editors

The current ZIP Editors are Daira Hopwood, representing the Electric Coin Company, and Josh Cincinnati, representing the Zcash Foundation. Both can be reached at zips@z.cash . The current design of the ZIP Process dictates that there are always at least two ZIP Editors: one from the Electric Coin Company and one from the Zcash Foundation. Additional Editors may be selected by consensus among the current Editors.

ZIP Editor Responsibilities & Workflow

The ZIP Editors subscribe to the Zcash Community Forum.

For each new ZIP that comes in an Editor confirms the following:

  • 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.
  • The title should accurately describe the content.
  • The ZIP draft must have been sent to the Zcash Community Forum or as a PR to the ZIPs git repository
  • Motivation and backward compatibility (when applicable) must be addressed.
  • The licensing terms are acceptable for ZIPs.

If the ZIP isn't ready, the editor will send it back to the Owner for revision, with specific instructions.

Once the ZIP is ready for the repository it should be submitted as a "pull request" to the ZIPs git repository where it may get further feedback. It should not contain a ZIP number, and should be labelled "WIP" in the pull request.

The ZIP Editors will:

  • Assign a ZIP number in the pull request.
  • Merge the pull request when it is ready and remove the "WIP" label.

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

The ZIP Editors MAY reject a proposed ZIP or update to an existing ZIP for any of the following reasons:

  • it violates the Zcash Code of Conduct [3] ;
  • 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 Draft ZIP to Released when 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);
  • in the case of a Released 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;
  • 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 been proposed for a category that does not reflect its content, or an update would change a ZIP to an inappropriate category;
  • it updates a Released ZIP to Draft when the specification is already implemented and has been in common use;
  • 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 [3] (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).

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.

Please send all ZIP-related communications either by email to <zips@z.cash>, or by opening an issue on the ZIPs issue tracker. All communications should abide by the Zcash Code of Conduct [3] and follow the GNU Kind Communication Guidelines

ZIP format and structure

ZIPs SHOULD be written either in reStructuredText [4] or LaTeX [5]. In the latter case, 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). The License field of the preamble indicates the licensing terms, which MUST be acceptable according to the ZIP licensing requirements.
  • 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.
  • 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. 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”, but it generally need not be completed before the ZIP is accepted into Proposed.

ZIP header preamble

Each ZIP must begin with an RFC 822-style header preamble. The following header fields are REQUIRED:

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

The following additional header fields are OPTIONAL:

Discussions-To:
Network Upgrade:
Obsoleted by:
Updated by:
Obsoletes:
Updates:

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.

While a ZIP is in private 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 Category header specifies the type of ZIP: Consensus, Standards Track, Informational, or Process.

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

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

There are several kinds of ZIP:

  • A Consensus ZIP describes a change that affects the consensus protocol followed by all Zcash implementations.
  • A Standards Track ZIP describes any non-consensus change that affects most or all Zcash implementations, such as a change to the network protocol, or any change or addition that affects the interoperability of applications using Zcash.

Consensus and Standards Track ZIPs consist of two parts: a design document and a reference implementation.

  • An Informational ZIP describes Zcash design issues, or general guidelines or information for the Zcash community, that do not fall into either of the above categories. Informational ZIPs do not necessarily represent a Zcash community consensus or recommendation, so users and implementers are free to ignore Informational ZIPs or follow their advice.
  • A Process ZIP describes a process surrounding Zcash, or proposes a change to (or an event in) a process. Process ZIPs are like Standards Track ZIPs but apply to areas other than the Zcash protocol itself. 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.

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

ZIP Status Field

  • Draft: All initial ZIP submissions have this status.
  • Withdrawn: If the Owner decides to remove the ZIP from consideration by the community, they may set the status to Withdrawn.
  • Active: Typically only used for Process/Informational ZIPs, achieved once rough consensus is reached in PR/forum posts from Draft Process ZIP.
  • Proposed: Typically the stage after Draft, added to a ZIP after consideration, feedback, and rough consensus from the community. The ZIP Editors must validate this change before it is approved.
  • Rejected: The status when progress hasn't been made on the ZIP in one year. Can revert back to Draft/Proposed if the Owner resumes work or resolves issues preventing consensus.
  • Implemented: When a Consensus or Standards Track ZIP has a working reference implementation but before activation on the Zcash network.
  • Final: When a Consensus or Standards Track 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).

More details on the status workflow in the section below.

Specification

Owners of a ZIP may decide on their own to change the status between Draft or Withdrawn.

A ZIP may 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 both the Electric Coin Company and Zcash Foundation Editors. One Editor will not suffice -- there needs to be consensus among the Editors. If it's a Standards Track ZIP, upon changing status to Proposed the Editors will add the optional Network Upgrade header to the preamble, indicating the intent for the ZIP to be implemented in the specified network upgrade. (All Network Upgrade schedules will be distributed via the Zcash Community Forum by the Editors.)

A Standards Track ZIP may only change status from Proposed to Implemented once the Owner provides an associated reference implementation, typically in the period after the network upgrade's specification freeze but before the implementation audit. If the Owner misses this deadline, the Editors or Owner(s) may choose to update the Network Upgrade header to target another upgrade, at their discretion.

ZIPs should be changed from Draft or Proposed status, to Rejected status, upon request by any person, if they have not made progress in one year. Such a ZIP may be changed to Draft status if the Owner provides revisions that meaningfully address public criticism of the proposal, or to Proposed status if it meets the criteria required as described in the previous paragraph.

A Consensus or Standards Track ZIP becomes Final when its associated network upgrade or other protocol change is activated on Zcash's mainnet.

A Process or Informational ZIP may change status from Draft 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 open to discussion on the forum or GitHub PR for at least one month, and no person maintains any unaddressed substantiated objections to it. Addressed or obstructive objections may be ignored/overruled by general agreement that they have been sufficiently addressed, but clear reasoning must be given in such circumstances.

When an Active or Final ZIP is no longer relevant, its status may 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).

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

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

Not acceptable licenses

All licenses not explicitly included in the above lists are not acceptable terms 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

References

[1]Key words for use in RFCs to Indicate Requirement Levels
[2]ZIP 200: Network Upgrade Activation Mechanism
[3](1, 2, 3) Zcash Code of Conduct
[4]reStructuredText documentation
[5]LaTeX -- a document preparation system
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