# Explicit RTL indication in pure Markdown

**URL:** <https://talk.commonmark.org/t/explicit-rtl-indication-in-pure-markdown/286>\
**Category:** Spec\
**Created:** [September 4, 2014, 12:12pm UTC](https://talk.commonmark.org/t/explicit-rtl-indication-in-pure-markdown/286 "2014-09-04T12:12:41Z")\
**Posts on this page:** 1\
**Showing post:** 9

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**Author:** ![mb21](https://talk.commonmark.org/user_avatar/talk.commonmark.org/mb21/32/162_2.png) [@mb21](https://talk.commonmark.org/u/mb21)\
**Post date:** [August 9, 2015, 12:09pm UTC](https://talk.commonmark.org/t/explicit-rtl-indication-in-pure-markdown/286/9 "2015-08-09T12:09:48Z")

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Okay, I’ve taken a look at the issue of [bidirectional text](https://en.wikipedia.org/wiki/Bi-directional_text) again. For a very accessible introduction, see [Unicode Bidirectional Algorithm basics](http://www.w3.org/International/articles/inline-bidi-markup/uba-basics). Quotes below are from [Unicode Standards Annex #9: The Bidirectional Alogrithm](http://www.unicode.org/reports/tr9/#Directional_Formatting_Characters).

If I understand correctly, as of Unicode 6.3 and later, the preferred way to do bidi text is to use two mechanisms only:

- Implicit Directional Formatting Characters: LRM (LEFT-TO-RIGHT MARK), RLM (RIGHT-TO-LEFT MARK) and ALM (ARABIC LETTER MARK) (ALM behaves the same as RLM, except around numbers). “Their effect on bidirectional ordering is exactly the same as a corresponding strong directional character; the only difference is that they do not appear in the display.”

- Marking up the direction of ranges of text, using either “Explicit Directional Isolate Formatting Characters” or better yet, when using a markup language like HTML, use the `dir` attribute or similar. “On web pages, the explicit directional formatting characters […] should be replaced by using the dir attribute and the elements BDI and BDO. This does not apply to the implicit directional formatting characters.” [BDI](https://developer.mozilla.org/en-US/docs/Web/HTML/Element/bdi) is only used when the directionality is not known, e.g. from user input saved in a db (thus doesn’t apply to markdown), and BDO is used to [override the normal bidirectionality rules](http://stackoverflow.com/a/19165097/214446) which seems like an edge-case that can be simulated by wrapping each character in an element with a dir attribute in the worst case (or do you think we’d really need a markdown BDO equivalent?)

Reading through [Authoring HTML: Handling Right-to-left Scripts](http://www.w3.org/TR/i18n-html-tech-bidi/), I tried to reproduce similar ‘funny’ behavior with markdown as well:

```
[مشس هخصث خهس تخت تخهثز](#العربي)

```

Note that this is a valid internal link in markdown, in any bidi-aware browser and editor, the `](#` are just displayed mirrored (i.e. rtl) since the surrounding text is rtl as well. But come to think about it, this is probably fine and could even be considered a strength of the markdown syntax (e.g. as opposed to HTML/XML). Similarly, markdown numbered lists display naturally for RTL scripts:

```
1. مشس هخصث خهس تخت تخهثز
2. مشس هخصث خهس تخت تخهثز

```

So… I think we could get away with “just” supporting the dir attribute, so you would write e.g. `The title is [مشس هخصث خهس تخت تخهثز!]{dir=rtl} in Arabic.`, where the `!` would be part of the title. However, this leaves the exclamation mark on the wrong side of the text when editing markdown, although it will be displayed correctly in a browser upon convertion to HTML. To display it correctly while editing markdown as well, you’d have to insert a ALM (or RLM) behind the `!` (of course, you need a [text editors that support bidi](https://en.wikipedia.org/wiki/Comparison_of_text_editors#Right-to-left_and_bidirectional_text) for this to work).

btw, can someone link to a good up to date resource about bidirectional text in LaTeX and ConTeXt? If found [this PDF](http://www.tau.ac.il/~stoledo/Pubs/eutupon.pdf), but it’s from 2001.

Basically the question is: if a markdown processor like Pandoc were to add native span and div syntax with the dir attribute and pass along unicode LRM, RLM and ALM chars:

1. this would already suffice for bidirectional HTML output, right?
2. what LaTeX and ConTeXt code would need to be emitted?

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