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PEP 545 -- Python Documentation Translations

PEP: 545
Title: Python Documentation Translations
Author: Victor Stinner <victor.stinner at>, Inada Naoki <songofacandy at>, Julien Palard <julien at>
Status: Draft
Type: Process
Created: 04-Mar-2017


The intent of this PEP is to make existing translations of the Python Documentation more accessible and discoverable. By doing so, we hope to attract and motivate new translators and new translations.

Translated documentation will be hosted on Examples of two active translation teams: will redirect to .

Sources of translated documentation will be hosted in the Python organization on GitHub: . Contributors will have to sign the Python Contributor Agreement (CLA) and the license will be the PSF License.


On the French #python-fr IRC channel on freenode, it's not rare to meet people who don't speak English and so are unable to read the Python official documentation. Python wants to be widely available to all users in any language: this is also why Python 3 supports any non-ASCII identifiers:

There are a least 3 groups of people who are translating the Python documentation to their native language (French [16] [17] [18] , Japanese [19] [20] , Spanish [21] ) even though their translations are not visible on d.p.o. Other, less visible and less organized groups, are also translating the documentation, we've heard of Russian [26] , Chinese and Korean. Others we haven't found yet might also exist. This PEP defines rules describing how to move translations on so they can easily be found by developers, newcomers and potential translators.

The Japanese team has (as of March 2017) translated ~80% of the documentation, the French team ~20%. French translation went from 6% to 23% in 2016 [13] with 7 contributors [14] , proving a translation team can be faster than the rate the documentation mutates.

Quoting Xiang Zhang about Chinese translations:

I have seen several groups trying to translate part of our official doc. But their efforts are disperse and quickly become lost because they are not organized to work towards a single common result and their results are hold anywhere on the Web and hard to find. An official one could help ease the pain.



Issue tracker

Considering that issues opened about translations may be written in the translation language, which can be considered noise but at least is inconsistent, issues should be placed outside (b.p.o).

As all translation must have their own github project (see Repository for Po Files ), they must use the associated github issue tracker.

Considering the noise induced by translation issues redacted in any languages which may beyond every warnings land in b.p.o, triage will have to be done. Considering that translations already exist and are not actually a source of noise in b.p.o, an unmanageable amount of work is not to be expected. Considering that Xiang Zhang and Victor Stinner are already triaging, and Julien Palard is willing to help on this task, noise on b.p.o is not to be expected.

Also, language team coordinators (see Language Team ) should help with triaging b.p.o by properly indicating, in the language of the issue author if required, the right issue tracker.


Translation teams should focus on last stable versions, and use tools (scripts, translation memory, …) to automatically translate what is done in one branch to other branches.


Translation memories are a kind of database of previously translated paragraphs, even removed ones. See also Sphinx Internationalization .

The three currently stable branches that will be translated are [12] : 2.7, 3.5, and 3.6. The scripts to build the documentation of older branches needs to be modified to support translation [12] , whereas these branches now only accept security-only fixes.

The development branch (master) should have a lower translation priority than stable branches. But docsbuild-scripts should build it anyway so it is possible for a team to work on it to be ready for the next release.


Domain Name, Content negotiation and URL

Different translations can be identified by changing one of the following: Country Code Top Level Domain (CCTLD), path segment, subdomain or content negotiation.

Buying a CCTLD for each translations is expensive, time-consuming, and sometimes almost impossible when already registered, this solution should be avoided.

Using subdomains like "" or "" is possible but confusing ("is it or ?"). Hyphens in subdomains like is uncommon and SEOMoz [23] correlated the presence of hyphens as a negative factor. Usage of underscores in subdomain is prohibited by the RFC1123 [24] , section 2.1. Finally, using subdomains means creating TLS certificates for each language. This not only requires more maintenance but will also cause issues in language switcher if, as for version switcher, we want a preflight to check if the translation exists in the given version: preflight will probably be blocked by same-origin-policy. Wildcard TLS certificates are very expensive.

Using content negotiation (HTTP headers Accept-Language in the request and Vary: Accept-Language ) leads to a bad user experience where they can't easily change the language. According to Mozilla: "This header is a hint to be used when the server has no way of determining the language via another way, like a specific URL, that is controlled by an explicit user decision." [25] . As we want to be able to easily change the language, we should not use the content negotiation as a main language determination, so we need something else.

Last solution is to use the URL path, which looks readable, allows for an easy switch from a language to another, and nicely accepts hyphens. Typically something like: "" or, by using a hyphen: "".

As for the version, sphinx-doc does not support compiling for multiple languages, so we'll have full builds rooted under a path, exactly like we're already doing with versions.

So we can have "" or "". A question that arises is: "Does the language contain multiple versions or does the version contain multiple languages?". As versions exist in any case and translations for a given version may or may not exist, we may prefer "", but doing so scatters languages everywhere. Having "/de/3.6/" is clearer, meaning: "everything under /de/ is written in German". Having the version at the end is also a habit taken by readers of the documentation: they like to easily change the version by changing the end of the path.

So we should use the following pattern: "".

The current documentation is not moved to "/en/", insted "" will redirect to "".

Language Tag

A common notation for language tags is the IETF Language Tag [3] [4] based on ISO 639, although gettext uses ISO 639 tags with underscores (ex: pt_BR ) instead of dashes to join tags [5] (ex: pt-BR ). Examples of IETF Language Tags: fr (French), ja (Japanese), pt-BR (Orthographic formulation of 1943 - Official in Brazil).

It is more common to see dashes instead of underscores in URLs [6] , so we should use IETF language tags, even if sphinx uses gettext internally: URLs are not meant to leak the underlying implementation.

It's uncommon to see capitalized letters in URLs, and doesn't use any, so it may hurt readability by attracting the eye on it, like in: " ". RFC 5646 (Tags for Identifying Languages (IETF)) section-2.1 [7] states that tags are not case sensitive. As the RFC allows lower case, and it enhances readability, we should use lowercased tags like pt-br .

It's redundant to display both language and country code if they're the same, for example: "de-DE" or "fr-FR". Although it might make sense, respectively meaning "German as spoken in Germany" and "French as spoken in France", it's not useful information for the reader. So we may drop these redundancies and only keep the country code for cases where it makes sense, for example, "pt-BR" for "Portuguese as spoken in Brazil".

So we should use IETF language tags, lowercased, like /fr/ , /pt-br/ , /de/ and so on.

Fetching And Building Translations

Currently docsbuild-scripts are building the documentation [8] . These scripts should be modified to fetch and build translations.

Building new translations is like building new versions so, while we're adding complexity it is not that much.

Two steps should be configurable distinctively: Building a new language, and adding it to the language switcher. This allows a transition step between "we accepted the language" and "it is translated enough to be made public". During this step, translators can review their modifications on d.p.o without having to build the documentation locally.

From the translation repositories, only the .po files should be opened by the docsbuild-script to keep the attack surface and probable bug sources at a minimum. This means no translation can patch sphinx to advertise their translation tool. (This specific feature should be handled by sphinx anyway [9] ).


Mailing List

The doc-sig [27] mailing list will be used to discuss cross-language changes on translated documentation.

There is also the i18n-sig list but it's more oriented towards i18n APIs [1] than translating the Python documentation.


Due to the Python community being highly active on IRC, we should create a new IRC channel on freenode, typically #python-doc for consistency with the mailing list name.

Each language coordinator can organize their own team, even by choosing another chat system if the local usage asks for it. As local teams will write in their native languages, we don't want each team in a single channel. It's also natural for the local teams to reuse their local channels like "#python-fr" for French translators.

Repository for PO Files

Considering that each translation team may want to use different translation tools, and that those tools should easily be synchronized with git, all translations should expose their .po files via a git repository.

Considering that each translation will be exposed via git repositories, and that Python has migrated to GitHub, translations will be hosted on github.

For consistency and discoverability, all translations should be in the same github organization and named according to a common pattern.

Given that we want translations to be official, and that Python already has a github organization, translations should be hosted as projects of the Python GitHub organization [28] .

For consistency, translation repositories should be called python-docs-LANGUAGE_TAG [22] , using the language tag used in paths: without region subtag if redundent, and lowercased.

The docsbuild-scripts may enforce this rule by refusing to fetch outside of the Python organization or a wrongly named repository.

The CLA bot may be used on the translation repositories, but with a limited effect as local coordinators may synchronize themselves with translations from an external tool, like transifex, and loose track of who translated what in the process.

Versions can be hosted on different repositories, different directories or different branches. Storing them on different repositories will probably pollute the Python github organization. As it is typical and natural to use branches to separate versions, branches should be used to do so.

Translation tools

Most of the translation work is actually done on Transifex [15] .

Other tools may be used later and

Contributor Agreement

Contributions to translated documentation will be requested to sign the Python Contributor Agreement (CLA):

Language Team

Each language team should have one coordinator responsible for:

  • Managing the team.
  • Choosing and managing the tools the team will use (chat, mailing list, …).
  • Ensure contributors understand and agree with the CLA.
  • Ensure quality (grammar, vocabulary, consistency, filtering spam, ads, …).
  • Redirect issues posted on b.p.o to the correct GitHub issue tracker for the language.

The license will be the PSF License , and copyright should be transferable to PSF later.


Simplified English

It would be possible to introduce a "simplified English" version like wikipedia did [10] , as discussed on python-dev [11] , targeting English learners and children.

Pros: It yields a single translation, theoretically readable by everyone and reviewable by current maintainers.

Cons: Subtle details may be lost, and translators from English to English may be hard to find as stated by Wikipedia:

> The main English Wikipedia has 5 million articles, written by nearly 140K active users; the Swedish Wikipedia is almost as big, 3M articles from only 3K active users; but the Simple English Wikipedia has just 123K articles and 871 active users. That's fewer articles than Esperanto!


Migrate GitHub Repositories

We (authors of this PEP) already own French and Japanese Git repositories, so moving them to the Python documentation organization will not be a problem. We'll however be following the New Translation Procedure .

Patch docsbuild-scripts to Compile Translations

Docsbuild-script must be patched to:

  • List the language tags to build along with the branches to build.
  • List the language tags to display in the language switcher.
  • Find translation repositories by formatting{language_tag}.git (See Repository for Po Files )
  • Build translations for each branch and each language.

Patched docsbuild-scripts must only open .po files from translation repositories.

List coordinators in the devguide

Add a page or a section with an empty list of coordinators to the devguide, each new coordinator will be added to this list.

Create sphinx-doc Language Switcher

Highly similar to the version switcher, a language switcher must be implemented. This language switcher must be configurable to hide or show a given language.

The language switcher will only have to update or add the language segment to the path like the current version switcher does. Unlike the version switcher, no preflight are required as destination page always exists (translations does not add or remove pages). Untranslated (but existing) pages still exists, they should however be rendered as so, see Enhance Rendering of Untranslated and Fuzzy Translations .

Update sphinx-doc Version Switcher

The patch_url function of the version switcher in version_switch.js have to be updated to understand and allow the presence of the language segment in the path.

Enhance Rendering of Untranslated and Fuzzy Translations

It's an opened sphinx issue [9] , but we'll need it so we'll have to work on it. Translated, fuzzy, and untranslated paragraphs should be differentiated. (Fuzzy paragraphs have to warn the reader what he's reading may be out of date.)

New Translation Procedure

Designate a Coordinator

The first step is to designate a coordinator, see Language Team , The coordinator must sign the CLA.

The coordinator should be added to the list of translation coordinators on the devguide.

Create Github Repository

Create a repository named "python-docs-{LANGUAGE_TAG}" (IETF language tag, without redundent region subtag, with a dash, and lowercased.) on the Python github organization (See Repository For Po Files .), and grant the language coordinator push rights to this repository.

Add support for translations in docsbuild-scripts

As soon as the translation hits its first commits, update the docsbuild-scripts configuration to build the translation (but not displaying it in the language switcher).

Add Translation to the Language Switcher

As soon as the translation hits:

  • 100% of bugs.html with proper links to the language repository issue tracker.
  • 100% of tutorial.
  • 100% of library/functions (builtins).

the translation can be added to the language switcher.


[1] [I18n-sig] Hello Python members, Do you have any idea about Python documents? ( )
[2] [Doc-SIG] Localization of Python docs ( )
[3] Tags for Identifying Languages ( )
[4] IETF language tag ( )
[5] GNU Gettext manual, section 2.3.1: Locale Names ( )
[6] Semantic URL: Slug ( )
[7] Tags for Identifying Languages: Formatting of Language Tags ( )
[8] Docsbuild-scripts github repository ( )
[9] ( 1 , 2 ) i18n: Highlight untranslated paragraphs ( )
[10] Wikipedia: Simple English ( )
[11] Python-dev discussion about simplified english ( )
[12] ( 1 , 2 ) Passing options to sphinx from Doc/Makefile ( )
[13] French translation progression ( )
[14] French translation contributors ( )
[15] Python-doc on Transifex ( )
[16] French translation ( )
[17] French translation github ( )
[18] French mailing list ( )
[19] Japanese translation ( )
[20] Japanese github ( )
[21] Spanish translation ( )
[22] [Python-Dev] Translated Python documentation: doc vs docs ( )
[23] Domains - SEO Best Practices | Moz ( )
[24] Requirements for Internet Hosts -- Application and Support ( )
[25] Accept-Language ( )
[26] Документация Python 2.7! ( )
[29] ( 1 , 2 )