Documentation style guide

This document focuses on style-guide. It is a kind of coding standards applied to documentation files. It is not about documentation content.

RestructuredText with Sphinx directives

This documentation uses Python-sphinx [1], which itself uses reStructuredText [2] syntax.


Use only lowercase alphanumeric characters and - (minus) symbol.

Suffix filenames with the .txt extension.


Usage of .rst extension is not recommended because:

  • RST files are human-readable text files. Most systems natively recognize the .txt extension and open these files with a text editor. This is a good choice.

  • Some programs parse .rst with rst2html [3], which cannot interpret some Sphinx’s directives such as code-block. So readers using such programs actually lose some content.

    As an example, well known Github [4] platform uses rst2html to render .rst files in its repository browser. Not only you lose content, you also lose features like links to lines.

  • When you need to read HTML builds of the documentation, best practice is to export documentation as static builds with sphinx-build command, then host and serve these builds as static files. For public projects, you may have a look at services like Read the docs [5].



Indent with 2 spaces.


  • toctree directive requires a 3 spaces indentation.

Blank lines

Two blank lines before overlined sections, i.e. before H1 and H2. One blank line before other sections. See Headings for an example.

One blank line to separate directives.

Some text before.

.. note::

  Some note.

Exception: directives can be written without blank lines if they are only one line long.

.. note:: A short note.

Line length

Limit all lines to a maximum of 79 characters.


Use the following symbols to create headings:

  1. # with overline
  2. * with overline
  3. =
  4. -
  5. ^
  6. "

As an example:

H1: document title

Introduction text.

Sample H2

Sample content.

Another H2

Sample H3

Sample H4

Sample H5

Sample H6

And some text.

If you need more than heading level 4 (i.e. H5 or H6), then you should consider creating a new document.

There should be only one H1 in a document.

Code blocks

Use the code-block directive and specify the programming language. As an example:

.. code-block:: python

  import this