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DCP: 0000
Title: DCP Process
Author: Dave Collins <davec@decred.org>
Status: Active
Created: 2017-05-04
License: CC0-1.0

Table of Contents

Abstract

A Decred Change Proposal, or DCP for short, is a design document that describes potential protocol or consensus changes to Decred. Due to Decred's decentralized governance structure, any proposed changes to consensus require super-majority stakeholder approval via the integrated on-chain proof-of-stake voting infrastructure. Consequently, DCPs primarily serve for documentation, fostering cross-implementation compatibility, and helping ensure proper engineering rigor is followed.

Prior to putting a consensus change to an on-chain vote, the proposed change must first be accompanied by a DCP as described in this document along with providing a working and tested implementation, and the rule change must be gated behind a voting agenda which ensures the stakeholders are provided with the opportunity to vote to accept or reject the change.

It is important to note that DCPs are intended to be the end result of an off-chain proposal and voting system that deals with more generalized proposal submissions. It is through that system that all initial proposals for consensus or protocol changes will be brought to life, undergo collaboration, and be subject to an initial community vote to determine if the work necessary to create a working implementation, its associated DCP, and an on-chain vote for the rule change should be performed.

However, the aforementioned proposal system is not yet available. This document will be updated with more details once it is available.

Formatting Specification

All DCPs must be written using the mediawiki format, and, where relevant, should be comprised of the sections detailed in this specification.

Header Preamble

Every DCP must begin with an RFC 822 style header preamble with the headers in the following order. Headers marked with an asterisk (*) are optional. All other headers are required.

  DCP: <DCP number, or "?" before being assigned>
  Title: <DCP title; maximum 44 characters>
  Author: <list of author names and email addresses>
  Status: <Defined | Voting | Locked In | Active | Failed | Replaced | Obsolete>
  Created: <date created on, in ISO 8601 (yyyy-mm-dd) format>
  License: CC0-1.0
* License-Code: <abbreviation for source code under different approved license(s)>
* Requires: <DCP number(s)>
* Replaces: <DCP number>
* Superseded-By: <DCP number>

The Author header lists the names and email addresses of all the authors/owners of the proposal. The format of the Author header value must be:

  Random J. User <address@dom.ain>

Multiple authors must be on a separate line following RFC 2822 continuation line conventions.

The Status header specifies the current status of the DCP as described in the status section.

The Created header records the date that the DCP was assigned a number. Dates must be in ISO 8601 (yyyy-mm-dd) format, e.g. 2017-05-04.

The License and License-Code headers must use approved licenses as defined in the licensing section.

DCPs may have a Requires header, indicating the DCP number(s) that the current one depends on.

DCPs may also have a Superseded-By header indicating that a DCP has been rendered obsolete by a newer version. The value is the number of the DCP that replaces the current one. The newer DCP must have a Replaces header containing the number of the DCP that it renders obsolete.

Standard Sections

The following sections are standard and thus should typically be included with all DCPs. There are some instances where some of the sections might not apply.

Abstract

The abstract section provides a short overview of the proposal. It is required for all DCPs.

Motivation

The motivation section explains in detail what the proposal addresses and why it is necessary. This section is critical and required for all consensus change proposals since consensus changes, in particular, must not be made lightly.

Consensus changes typically involve updates to a wide amount of software across the entire ecosystem and, at the very least, require stakeholder participation in the form of education and voting. In short, consensus changes often require the extremely valuable commodities of time and attention from everyone in the ecosystem and, as such, must have a compelling motivation.

Specification

The specification precisely describes the semantics of the proposal. In particular, it must be detailed enough to foster multiple interoperable implementations of Decred software.

It is important to consider the implications of cross-platform compatibility when providing a specification since it is also critical to achieve the aforementioned goal of fostering multiple implementations.

For example, floating point math often produces slightly different results between programming languages due to issues such as rounding errors and uncertainty in their respective libraries. Consequently, integer math is generally preferred.

Another example is that the precision of regular integers in some languages may vary depending on the architecture (e.g 32-bit versus 64-bit). Specifications must consider these differences and ensure they are adequately defined.

Morever, consensus code must strive to actively avoid 3rd-party dependencies since other projects often have very different, and less strict, requirements than what is required by consensus code.

Rationale

The rationale section provides insight into the final design laid out in the specification. It should include topics such as why particular design decisions were made, theory of operation, alternate designs, and other related work.

This section, like the motivation section, is also critical and required for consensus change proposals. Stakeholders need to make an informed decision on any new rules introduced to the network and the rationale for choosing a particular design is a key consideration.

Keep in mind that fully validating nodes will be responsible for enforcing any rules set forth by the proposal and archival nodes will effectively have to enforce the rules forever.

Deployment

The deployment section provides details related to how the proposal will be deployed to the network.

As mentioned in Abstract section of this document, all consensus changes must make use of a voting agenda.

The voting agenda definition should be of the following form:

Name Setting
Deployment Version version
Agenda ID short, descriptive agenda id
Agenda Description description of the agenda
Start Time unix timestamp (human-readable date)
Expire Time unix timestamp (human-readable date)
Mask agenda mask in hex that defines which bits are used (Bits #, #, ...)
Choices
Choice English Description Bits
abstain short description of the choice 0x00
no short description of the choice value of choice in hex (Bit #)
option 1 short description of the choice value of choice in hex (Bit #)
option 2 short description of the choice value of choice in hex (Bit #)

Compatibility

The compatibility section is recommended for all proposals and is required for any proposals that introduce backwards incompatibilities. In general, this section should discuss exactly how the proposal affects existing software.

A proposal that is backwards compatible should specifically state that, along with an explanation of why it is backwards compatible.

A proposal that is not backwards compatible must also provide a plan for handling the incompatibilities.

Reference Implementation

The reference implementation section is required for all consensus change proposals since, due to Decred's decentralized governance structure, all proposals which involve changes to consensus must undergo a voting agenda which implies that proposals must also already have a working, tested, and well-documented implementation that lies dormant in the code and therefore can be activated should the change be accepted by the stakeholders.

Test Vectors

The test vectors section applies to any proposals that introduce facets that can reasonably be independently tested and serves to help multiple implementations ensure they are compatibile. Some examples where test vectors might reasonably be included are new algorithms, new standard script types, smart contracts, additional script opcodes, and changes to the block or transaction structure or hash generation.

Acknowledgements

The acknowledgements section provides a standard mechanism for giving recognition. This might include citing contributors and collaborators who provided direct technical assistance, participated in intellectual discussions, or otherwise provided assistance with the proposal.

This section also should be used to cite relevant source material as needed.

Acknowledgements that are not directly related to the proposal, such as personal encouragement, should not be included.

Copyright

All DCPs must be licensed under the terms set forth in the Licensing section.

Other Sections

In addition to the standard sections, the DCP may contain any other sections that the author feels are relevant to the proposal. For example, some proposals may wish to contain supplemental data such as simulation results, examples, footnotes, and future extensions.

Status

Specification

The status of a DCP is primarily defined by the on-chain voting sytem. There are two additional status indicators intended to allow clear DCP status signalling in case future updates replace or obsolete a given DCP.

The following chart shows the progression of a DCP according to the voting process:

DCPs which involve a consensus change automatically progress to the Voting, Locked In, Active or Failed status depending on the result of the associated on-chain vote.

It is also possible for the semantics defined by a DCP to be replaced or rendered obsolete by a newer DCP. In that case, the status may become Replaced or Obsolete.

Rationale

One of the most important features of Decred is its democratic handling of potentially controversial consensus changes via its decentralized, transparent, cryptographically-secured, on-chain voting system. This means that whether or not a given consensus change proposal progresses to an Active or Failed status is entirely based on the results of the on-chain vote.

There are no additional status indicators for things such a drafts and withdrawals since all DCPs are only created as the result of an off-chain proposal and voting system that deals with those issues has already been completed.

Licensing

Specification

DCP Text

New DCPs are required to be licensed with the CC0-1.0: Creative Commons CC0 1.0 Universal license and must declare this by setting the License header in the preamble to its abbreviation, CC0-1.0.

Source Code

The source code in the DCP may optionally be licensed using a separate license per the following list. The separate code license must be declared by setting the License-Code header in the preamble to its abbreviation.

The recommended license for source code is ISC.

Rationale

It is important for DCPs to be licensed under the most permissive terms possible since they will become technical reference documents that are an intrinsic part of Decred. This is also why code licenses such as the GPL are not acceptable.

While it might be tempting to simply allow DCPs to placed into the public domain directly, it is disallowed due to its controversial legal status. The public domain is not universally recognized as a legally sanctioned entity, so some argue that "granting" a work into the public domain has no legal effect whatsoever.

Acknowledgements

This process was heavily influenced by the Bitcoin Improvement Proposal (BIP) process although it has been modified to fit the needs of Decred. The BIP process document from which portions of this document are based is licensed under the BSD-2-Clause license by author "Luke Dashjr <luke+bip@dashjr.org>".

Thanks to the following individuals who provided valuable feedback during the review process of this proposal:

  • Jake Yocom-Piatt

Copyright

This document is licensed under the CC0-1.0: Creative Commons CC0 1.0 Universal license.