not just metadata, but "attention metadata". as i understand it, its the idea to go beyond words; to look and analyze any interaction that any person ever had with a text. the "any" comes form erik duval, who is doing a workshop on this.

Facilitating the usage of contextualized attention metadata is a cross-disciplinary research topic that combines research results and challenges from communities including databases, information retrieval, knowledge representation, knowledge management, user modeling, recommender systems, learning technologies, etc. | contextualized attention metadata