AOSL & XAOSL Formats


AOSL is a universal format for digital story-telling.

AOS Overview

(In this diagram, you can see that AOSL is the central format on which all our projects relies on.)

As all AOS projects, AOSL is open-source and free of charge (MIT license), which mean anyone can use it, build tools or players for it.

The current version of AOSL is 1.0. This format is still young so it’s still evolving a lot.

AOSL‘s purpose is to be able to describe any kind of born-digital stories:

  • composed of any kind of media (images, sounds, videos, animations, games..);
  • with or without effects in transitions (between each step into the story);
  • linear or not (with branches and loops and other procedural constructs);

Basically, AOSL can represent born-digital stories exploiting the procedural nature of digital platforms.

Digital stories authors should not care about technical details of how it works inside. However, they should know that AOSL impose only two natural structural restrictions on the stories:

  1. graphic content will be displayed in a graphic canvas which have a size fixed for the whole story (basically, a screen);
  2. a story is structured as a sequence of stages, with transitions between each stage (which can optionally have effects);

That’s all! Each player implementation, which can read an AOSL story, will impose some other limitations, but AOSL itself have none.

You can find examples of such born-digital stories there.

AOSL is also designed to work easily with tools.Actually, all Art Of Sequence tools work with AOSL. This means that it is not difficult for developers to build:

  • players that can read directly AOSL – like AOS Web Player;
  • exporters that convert a story in AOSL to the same story in another format (Flash/Air, native smartphone application, etc.);
  • edition tools (like AOS Designer);

If you are a developer and want technical details about the format, check the documentation or take a look at the code.


XAOSL (pronounced ‘xao-ess-el’) is another format, based on AOSL, which is designed to be used in a wide variety of use cases.

Basically, XAOSL is designed to allow authors to have their full story with all images, sounds, etc. inside only one file that they can put in any player that can read AOSL.

To sum up, it’s just an archive file (a zip file) which contain both AOSL data and the media files used by the story, all together in one package file. It impose additional restrictions on the content, like it can only contain media that can be read by a internet browser, but it’s still very generic and useful.

It is inspired by the epub format for it’s ease of use, but differ in the way the content is diffused.

For developers, XAOSL specification is in the same code repository than AOSL.


The XSD files specifying AOSL format are available there:

You can also get specific versions of both documentations and XSD code there.