Synthetic characters are an effective modality to convey messages to the user, provide visual feedback about the system internal understanding of the communication, and engage the user in the dialogue through emotional involvement. In this paper we argue for a fine-grain distinction of the expressive capabilities of synthetic agents: avatars should not be considered as an indivisible modality but as the synergic contribution of different communication channels that, properly synchronized,

more »

... te an overall communication performance. In this view, we propose SMIL-AGENT as a representation and scripting language for synthetic characters, which abstracts away from the specific implementation and context of use of the character. SMIL-AGENT has been defined starting from SMIL 0.1 standard specification and aims at providing a high-level standardized language for presentations by different synthetic agents within diverse communication and application contexts.