// Copyright 2014-2023 The Khronos Group Inc.
//
// SPDX-License-Identifier: CC-BY-4.0

[[introduction]]
= Introduction

This document contains required procedures and conventions when writing
specifications for new Vulkan APIs, extensions and layers, or related
Khronos^{reg}^ documentation such as white papers and tutorials; or
contributing to existing Vulkan specifications.
These are collectively referred to as _Vulkan Documentation_ or just
_documentation_ below.
The primary focus is the API Specification and API extensions, although all
of the markup and most of the writing style is equally applicable to other
documentation.

The primary purpose is to achieve consistency across the API, as well as
across all of our source and output documents.
Consistency makes it easier for developers, editors, reviewers, and users of
our documentation to understand and modify it.

This document is now formally voted on and approved by the Vulkan Working
Group.
This means that unless explicitly stated otherwise, the procedures and
conventions must be followed.
If you have a strong desire to modify the procedures and conventions, such
changes must be made through the normal Vulkan Working Group processes.


[[introduction-terminology]]
== Terminology

The key words *must*, *required*, *should*, *recommend*, *may*, and
*optional* in this document are to be interpreted as described in RFC 2119
and by the Vulkan Specification in the "`Terminology`" section.


[[introduction-structure]]
== Document Structure

The style guide is broken into four sections:

  * <<naming,API Naming Conventions>> - the required rules for choosing
    names of Vulkan identifiers of all types.
  * <<extensions,Extensions and Layers>> - the required procedures for
    creating formal Vulkan extensions and layers.
  * <<markup,Markup Style>> - the required and recommended markup style for
    writing asciidoctor and XML source that follows consistent formatting
    and layout guidelines, tags special terms and phrases for proper
    processing by the spec generation tools, etc.
  * <<writing,Writing Style>> - the required and recommended writing style
    for overall and fine-grained structure and conventions, normative
    language use, API naming conventions, common words and phrases to use
    and to avoid, linking and cross-referencing, etc.


[[introduction-asciidoc]]
== Asciidoctor Markup

Vulkan Documentation is primarily written in Asciidoctor, a text markup
language.
We use the command-line asciidoctor client that is actively maintained by
asciidoctor, which is documented on its website at https://asciidoctor.org.

References to the Asciidoctor User Manual are to sections in the document at
https://asciidoctor.org/docs/user-manual/.

Asciidoctor is implemented in Ruby (https://www.ruby-lang.org/), which is
available for Linux, MacOS, and Microsoft Windows.

[NOTE]
.Note
====
There are other implementations of asciidoctor, such as AsciidoctorJ
(https://github.com/asciidoctor/asciidoctorj) and asciidoctor.js
(https://github.com/asciidoctor/asciidoctor.js).
In particular, GitHub and GitLab both have preview renderers for .adoc or
.asciidoc files in repositories, and live preview extensions exist for
Chrome and Firefox.

However, because of the use of custom Ruby macros in the Vulkan
Specification toolchain, and the high complexity of the documents and
toolchain used to generate it, these web tools cannot currently render the
Specification from source.
Instead, we generate HTML and PDF versions of the Specification and publish
them on the Khronos website.

The Asciidoctor toolchain and build process are not addressed by this
document, which concentrates solely on source documents.
====


[[introduction-normative]]
== Normative References

Normative references are references to external documents or resources to
which documentation authors must comply.

[[acm-references]]
Association for Computing Machinery.
_Citation Style and Reference Formats_.
Retrieved July 27, 2019.
https://www.acm.org/publications/authors/reference-formatting .

[[iso-8601]]
International Organization for Standardization.
_Data elements and interchange formats -- Information interchange --
Representation of dates and times_ (2004-12-01).
https://www.iso.org/standard/40874.html .
Also see https://www.w3.org/QA/Tips/iso-date for colloquial examples.

[[vulkan-docs]]
Khronos Vulkan Working Group.
`KhronosGroup/Vulkan-Docs` project on GitHub (July 5, 2016).
https://github.com/KhronosGroup/Vulkan-Docs .

[[vulkan-registry]]
Jon Leech.
_The Khronos Vulkan API Registry_ (February 26, 2023).
https://registry.khronos.org/vulkan/specs/1.3/registry.html .

[[vulkan-spec]]
Khronos Vulkan Working Group.
_Vulkan 1.3.242 - A Specification_ (February 26, 2023).
https://registry.khronos.org/vulkan/ .

Version 1.3.242 is the latest patch release of the Vulkan API Specification
as of the time this reference was last updated, but the Specification is
frequently updated with minor bugfixes and clarifications.
When a more recent patch release is made, it becomes the normative reference
for the API.