Current business information systems extensively rely on graphical user interfaces (GUIs). These sub-systems enable the interaction between the end user and application kernel services that are essential for the business process instances. Due to dynamic and rapid changes of both business processes and their required services, a strong need for the quick adaptation of GUIs to the occurring changes arose. As both efficiency and usability are essential for the GUI adaptation, model-based development processes that involve patterns and their instantiation for specific GUI contexts have been suggested by ongoing research. Being based on human computer interaction patterns, the new kind of pattern needs to be formalized in order to enable the automated processing of configurable instances by generator tools. However, current research is still at the edge to express the concepts for such generative user interface patterns. Crucial factors and impacts of those patterns have not been described sufficiently yet so that a standardized format for the expression of variability is still missing. With our work, we briefly review the current state on modeling user interface patterns and their requirement aspects. The ultimate objective of this paper is the development of an analysis model that is able to express both the structure and variability concerns of user interface patterns in detail. To evaluate and illustrate the analysis model concepts, selected user interface pattern instances are modeled via object models. As result, a detailed description of generative user interface patterns is achieved, which can be applied as a basis for the verification of recent approaches of model- and pattern-based GUI development or even the synthesis of a dedicated user interface pattern language.