We present a field study aimed at analysing the use of viewpoints in co-design meetings. A viewpoint is a representation characterised by a certain combination of constraints. Three types of viewpoints are distinguished: prescribed viewpoint, discipline-specific viewpoint and integrated viewpoint. The contribution of our work consists in characterising the viewpoints of various stakeholders involved in co-design ("design office" disciplines, and production and maintenance disciplines), the dynamics of viewpoints confrontation and the cooperative modes that enable these different viewpoints to be integrated.