Transmedial worlds - Rethinking Cyberworld Design
http://www.itu.dk/people/klastrup/klastruptosca_transworlds.pdf

Paper relating Genre and adaptation theory to transmedial world creation.

“Transmedial worlds are abstract content systems from which a repertoire of fictional stories and characters can be actualized or derived across a variety of media forms . What characterizes a transmedial world is that audience and designers share a mental image of the worldness.... The idea of specific world worldness mostly originates from the first version of the world presented, but can be elaborated and changed over time”

Translation - a transmedial world offers the opportunity to tell a variety of stories set in the same world across a range of media platforms. Both the author and consumer accept and understand the rules of that world and apply them to any stories set in that world.

Stories set in a world may be considered actualizations of that world.

The success of any transmedial project depends upon the interest of the interpretive community- the audience consuming it- it is they that must be interested in exploring the world beyond the simple story in front of them. Whether the world is developed through  fan fiction or vier corporate planning it is the interest of this interpretive community is central to its success.

interpretive community: By way of introducing the concept of interpretive communities, Fish argues that the informed reader's interpretive perceptions and aesthetic judgments are not idiosyncratic but socially constructed; they depend heavily on the assumptions shared by the social group or groups to which the reader belongs. Interpretive communities adopt particular kinds of reading strategies which will, in due course, determine the entire reading process, the stylistic peculiarities of a literary text as well as the experience of assimilating them.
http://www.blackwellreference.com/public/tocnode?id=g9780631207535_chunk_g978063120753512_ss1-12

Although they are talking about the interest of the fan necessary to  encourage development , there is no mention of the feelings of ownership that often accompany the cult status and near worship by the fans of the relevant transmedial world.

The transmedial world of accepted rules understood by both author and consumer relates in many ways to the world of the creative Genre.

Genres can be defined as patterns / forms / styles / structures which transcend individual art products and which supervise both their construction by artist and reading audiences. Basic requirement of a genre is that there is more than one product with  a  basic structure that the audience will be able to recognise when reading another story. Although Genre are found on all media platforms , it is not unusual for the most success representatives of their genre to transfer to other medias , you therefore have cowboy books , plays and films etc.

Suggestion in this article that Genres and transmedial worlds work in very similar ways save one significant difference namely, that within the transmedial world all stories share one basic foundation story.... Nick Lancy suggests almost a Genre template consisting of setting character, narrative iconography, style and stars....

I would suggest that the most significant element that is missing in this proposition is the interactive element of transmedial narrative. It is the audience participation that as far as I am concerned offers the biggest differentiator between a genre and a transmedial world.

The possibility could be offered in response to this argument that interaction may occur through necessity to read stories across media platforms, in selecting their path through the story the consumer may be said to interacting with that story.

Narrative is independant from the medium in which it is to be found.Marie-Laure Ryan- narrative is a metal process or image stimulated when the appropriate trigger is depressed....

Key elements to transmedial project :
Mythos: The background story - the myth that runs behind the other stories, the myth that gives fundamental shape to the world.
Topos:  The time and place in which the world is set : The physical setting of the story.
Ethos: the explicit and implicit ethics of the world.

These are interesting ideas and I certainly agree they form part of a transmedial project but I do not feel that on there own they bring everything that is required for a project to be truly transmedial , perhaps it is better to think of them as part of the framework of a story that can if other appropriate elements are present could be called a transmedial project.