In CatchBob!, the messages which deals with strategy could discriminated with the following characteristics:- content: Bob's position, Bob's approximate location (area), the proper triangle configuration, advice/order abotu spatial behavior, a meeting point and network problems. - the adressees: A,B,C,B+C,A+B+C - temporal aspects: at which moment in the process a message is relevant - temporal evolution: refinement/modification of a message - coordination strategy: manifest/explicit agreement/convention (Clark's typology)

The point is to have a structured interface which will graphically represents those messages and help players to communicate these information. I will then run a new experiment with this new interface and logged information about the usage of such an interface (nb of clicks on each button and when) will allow me to check the validity of my model (the coordination strategies in mobile collaboration).