How is 'reader mode' in Firefox triggered?
Firefox on Android uses readability.js as the basis for its "Reader Mode" support. Here is a content guide for making pages that are easy to extract content:http://www.readability.com/developers/guidelines
The original readability code used in Firefox comes from:http://code.google.com/p/arc90labs-readability/
Note that not all pages can be converted into Reader Mode, in fact, that's not the intention. If you come across a page that you think should be handled by Reader Mode, please file an issue in the github issue tracker:
The developer of this features just reply via Twitter :
@edouard_lopez No docs, sorry. It finds for the main content of the page based on a number of things (tag name, classes, id, etc).