The issue of process automation is their desire to change. When business processes are automated using web-based workflow systems (WWS), process evolutions and changes need to be reflected in these implemented systems. Evolutions in business processes essentially mean altering process elements - actions, participants, object, and rules. In a process, elements are interlinked and woven together to achieve business objectives of an organization. Thus, a change in one element creates propagating impact on the other elements that are linked to it. Therefore, it is critical to understand constraints, associations and dependencies (CAD) among process elements for effective management of process evolution in WWS. Previous studies on CAD among process elements mostly focus on (at most) one or two process elements at a time. This paper brings together these isolated works into a single CAD model of process elements. Cohesive and complete nature of this model, lays the foundation to effective management of process evolution in WWS.