Although primarily studied in the context of product lines, variability is a key fact about most systems and therefore a concern for the architectures of those systems. Thus it is essential for the Architect to have suitable tools for representing, managing and reasoning about variation. Most work on product line variation has focused on the variability of components and their connectors within an architecture. Meanwhile, Architects today often use multiple viewpoints to frame diverse stakeholders' concerns for an architecture.  How can variation be expressed within the representational paradigm of multiple viewpoints?  This paper uses a simplified model of variation reflecting current practice and explores the consequences of that model for the representation of variation as a part of architecture description, using the conceptual foundation of ISO/IEC 42010 (the revision of IEEE 1471:2000) and poses a number of questions for discussion at the VARI-ARCH workshop.
['R. L. Hilliard']
On representing variation