Feature Diagrams (FD) are widely used in software product line engineering [PBL05] to document variability. In general, a FD is a tree or a directed acyclic graph that serves as a compact representation of all valid combina-tions of its nodes. Those nodes (except the root node) are usually called features. The root node is called the ?concept?.
In software product line engineering, two kinds of variability can be distin-guished: Software variability and PL variability.
Software variability refers to the ?ability of a software system or arte-fact to be efficiently extended, changed, customized or configured for use in a particular context? [SGB05].
PL variability is specific to SPLE and describes the variation between the systems that belong to a PL [CHW98, PBL05, KLD02] in terms of properties and qualities, like features that are provided or require-ments that are fulfilled. It is important to understand that defining PL variability, i.e. determining what should vary between the systems in a PL and what should not, is an explicit decision of product man-agement (see [KLD02, PBL05]).
This tech report presents a collection of feature diagrams that we have found in the research literature with the aim of determining from those fea-ture diagrams, which kind of variability has been documented.
There are many FD dialects. Besides a collection of examples, this tech re-port also gives an overview of those various dialects and the concrete syn-taxes (notations) they employ.