In this paper we propose a contribution to the realization of a model-driven systems engineering vision: an initial analysis towards the design of a unified modelling language built upon IEC 61850. To efficiently profit from the advantages and manage the flexibility and complexity of full IEC 61850 systems, engineers need not only to exchange models of the system, but also to straightforwardly understand them during the whole system life-cycle. For this purpose a standard exchange format is required (ex: IEC 61850-6 SCL), but a standards-based visual language would constitute a unique industry enabler by increasing model understandability for the user from design, through implementation and testing, up to operation and maintenance. Throughout the paper authors present proposals of diagrammatical notations and corresponding use cases as well as introduce an on-going substation application. (4 pages)