We consider how to handle open walking areas in pedestrian navigation applications. Walking areas are a key type of feature which is a major difference between networks of pedestrian navigation and that of road vehicle navigation. Up to recently, little work has been carried out on these features though they are important to route planning algorithm design and path representation for pedestrian navigation. Characteristics of walking areas are classified into three types with orthogonal attributes, including the character of boundaries and entrances, concavo-convex characteristics of shapes and the presence and numbers of islands. The possible combinations are identified and general solutions proposed. Future work including the extension to 3D navigation in buildings and trials in mobile applications are proposed.