Authors guide#

This guide is for authors of Plone Documentation. It covers how to run a live preview of documentation while editing, build documentation, and perform quality checks. For general markup syntax, see MyST reference.

Synchronize the browser while editing#

Use sphinx-autobuild to view changes in the browser while you edit documentation.

make livehtml

You can open a browser at to preview the documentation.

Quality checks#

We strive for high quality documentation, setting the following minimum standards.

Markup syntax must be valid#

See both the specific markup syntax above and general markup in MyST reference.

To validate markup, run the following command.

make html

Open /_build/html/index.html in a web browser.

American English spelling, grammar, and syntax, and style guide#

Vale is a linter for narrative text. It checks spelling, English grammar, and style guides. Plone uses American English.

Vale also provides English grammar and syntax checking, as well as a Style Guide. The Plone Documentation Team selected the Microsoft Writing Style Guide for its ease of use—especially for non-native English readers and writers—and attention to non-technical audiences.

To perform all these checks, run the following command.

make vale

Because it is difficult to automate good American English grammar and syntax, we do not strictly enforce it. We also understand that contributors might not be fluent in English. We encourage contributors to make a reasonable effort, and to request a review of their pull request from community members who are fluent in English to fix grammar and syntax. Please ask!


More corrections to spellings and Vale's configuration are welcome by submitting a pull request. This is an easy way to become a contributor to Plone. See Advanced Vale usage for details.

Advanced Vale usage#

To have Vale check only a specific file or directory of files, you can issue Vale commands with options in a shell session. To allow this, you must either:

  • activate your Python virtual environment

  • use the virtual environment path, such as bin/vale

  • install Vale using operating system's package manager

The Vale Makefile command automatically installs Vale into your Python virtual environment—which is also created via any documentation Makefile commands—when you invoke it for the first time.

Vale has integrations with various IDEs. Integration might require installing Vale using operating system's package manager.

Plone configures Vale in three places:

  • .vale.ini is Vale's configuration file. This file allows overriding rules or changing their severity.

  • Makefile passes options to the vale command, such as the files Vale checks.

  • Plone documentation uses a custom spelling dictionary, with accepted and rejected spellings in styles/Vocab/Plone. Authors should add new words and proper names using correct casing to styles/Vocab/Plone/accept.txt, sorted alphabetically and case-insensitive.

Syntax highlighting#

Pygments provides syntax highlighting in Sphinx.

When including code snippets, you should specify the language. Authors must use a proper Pygments lexer and not generate warnings.

The snippet must be valid syntax for the language you specify, else it will not be highlighted properly. Avoid adding comments to code snippets, unless you use valid comment syntax for that language. For example, JSON does not allow comments.

Do not indicate elided or omitted code with ellipses (... or ). These are almost never valid syntax and will cause syntax highlighting to fail for the code block.

Choosing a Lexer#

Some lexers are less than perfect. If your code block does not highlight well, then consider specifying a less ambitious lexer, such as text.

Use shell for commands to be issued in a terminal session. Do not include shell prompts. This will make commands easy to copy and paste for readers.

Use console for output of a shell session. If you have a mix of a shell command and its output, then use console.

If xml does not work well, then try html.

jsx has a complex syntax that is difficult to parse. We have high hopes for the project jsx-lexer. We include it in our requirements.txt file. Please contribute to its further development.

The lexers html+ng2, scss, http, less are also suboptimal and particular.

If no other lexer works well, then fall back to text. At least then the build will succeed without warnings, although syntax highlighting for such snippets will not appear.

Validate the lexer#

Always build the page to validate syntax. The change should not be merged if there are any Sphinx warnings. The Sphinx console will display any warnings, such as the following.

/Plone/documentation/classic-ui/ WARNING: Could not lex literal_block as "python". Highlighting skipped.

The above warning indicates that the syntax is not valid. Common mistakes include:

  • Using ... or to indicate omitted code. It is preferable to never use ellipses. If you must do that, comment it out using the language's comment syntax.

  • Using comments in JSON.

  • A previous code block bleeds through to the next due to invalid MyST syntax.

To validate code block syntax, run the following command.

make html

An online demo of all lexers that Pygments supports may be helpful to test out your code blocks and snippets for syntax highlighting. You can also use the pygmentize binary.

When using the online lexer, if any red-bordered rectangles appear, then the lexer for Pygments interprets your snippet as not valid. You can search the Pygments issue tracker for possible solutions, or submit a pull request to enhance the lexer.

HTML and Open Graph metadata#

All documents must have a myst topmatter key with an html_meta directive at the top of every page. When rendered to HTML, it inserts <meta> tags for improved search engine results and nicer social media posts. Authors should include at least description, property=og:description, property=og:title, and keywords meta tags.

The following is an example of html_meta. Note that the content of the two tags description and property=og:description should be identical.

    "description": "Authors' guide to writing Plone Documentation. It covers configuring quality checks and syntax for writing markup that is of particular interest to authors."
    "property=og:description": "Authors' guide to writing Plone Documentation. It covers configuring quality checks and syntax for writing markup that is of particular interest to authors."
    "property=og:title": "Authors Guide"
    "keywords": "Plone, Documentation, SEO, meta, Vale, spell, grammar, style, check, linkcheck, lexer"

This renders in the HTML <head> section as follows.

<meta content="Authors' guide to writing Plone Documentation. It covers configuring quality checks and syntax for writing markup that is of particular interest to authors." name="description" />
<meta content="Authors' guide to writing Plone Documentation. It covers configuring quality checks and syntax for writing markup that is of particular interest to authors." property="og:description" />
<meta content="Authors Guide" property="og:title" />
<meta content="Plone, Documentation, SEO, meta, Vale, spell, grammar, style, check, linkcheck, lexer" name="keywords" />

Additional Open Graph metadata is implemented through the Sphinx extension sphinxext-opengraph and the MyST html_meta directive, which resolves to the Docutils meta directive. See the site-wide configuration in

Plone documentation styleguide#

We follow Microsoft Writing Style Guide.

Key concepts from that guide include the following.

  • Documentation should be informational, but friendly.

  • Address the reader by using "you" instead of "the user".

  • Headings should be Sentence cased, not Title Cased.

The Plone Documentation Team adopted additional guidelines.

  • Use one sentence per line. Keep sentences short and understandable. This will greatly improve the editing and maintenance of your documentation.

  • Do not follow PEP8 maximum line length standard. Documentation is narrative text and images, not Python code.

  • Use dashes - in filenames and avoid underscores.

  • Images should be no wider than 740 pixels to fit within the documentation's main view port. This avoids scaling and reducing legibility of images. To make that work in Volto, set your browser width to 1180 pixels. You will notice that the drag and trash icons for each block move inside the block from outside.

  • In user documentation, provide screenshots of each step where the interface changes. It is painstaking, but worth the effort. Provide sufficient detail of what each option is and does.

General documentation writing references#