This article presents graphical modelling concepts, especially for the modelling of socio-technical processes. This requires the representation of those parts of knowledge which cannot be stated definitely and have to be modelled vaguely. The presented modelling concepts allow the extension of existing graphical and textual modelling methods to model facts without making unnecessary and unwelcome commitments about not already completed knowledge. In the same way, it also allows the modelling of facts which cannot be modelled completely, like aspects of social systems comprising of cooperation and communication. A special modelling notation (SeeMe) is used to present the concepts. A systematic differentiation of vagueness shows the alternative ways for modellers to express vague facts. Expressing undetermined decisions is another element of vague modelling in SeeMe.