The work reported here relates to the need for collaborative platforms for sharing knowledge in engineering design. Such platforms often integrate different indicators for describing or measuring the characteristics of current or past activities in order to improve collaboration. These collaboration indicators are intended to promote the interaction between the users of those platforms, and to provide engineers with different forms of awareness. In this paper, the issue of defining a structured approach for building a consistent set of indicators for an efficient collaborative platform in engineering design is investigated. A possible classification for these indicators is put forward and is based on several dimensions, such as the social aspects. This classification provides a broad view of indicator requirements, through grid, making it possible both to analyse existing indicators and to characterise users' needs in order to define new ones. The proposed classification is tested in two different companies using a collaborative platform for their engineering activities. It is shown that the classification makes it possible to reveal the strengths and weaknesses of an existing set of indicators, and how it can support the elicitation process of new ones. Finally, a definition of co-design methodology for collaboration indicators is suggested. Here, particular attention is paid to users' needs and to the systematic consideration of all relevant dimensions.