Traceability of an interface indicates its ability to guide users in accessing a piece of existing information. This metric examines a frequent task in most information management interfaces, where the user is incrementally tracing the information hierarchy of the interface to track down the location of a piece of information by examining composite node instances at each level.
Traceability can be examined by following successive footprints to a node instance. One measure could be successive multiplication of footprint values for each link along the path. It is important to examine footprints in succession since a weak link on the path may decrease the overall traceability of the interface.
An examination of the footprint measure in the WebBook and the Web Forager interface yields that a low footprint at the page-book link seems to affect all the remaining links (i.e. book-desk, book-shelf, book-air). For the vtwm interface, there is only a single path in the information hierarchy. Thus, each link is crucial. Yet, the footprint values seem be to satisfactory for most purposes. The Elastic Windows interface is, on the other hand, fairly traceable as the footprint values at each link is high due to visibility of contents. However, depending on the depth of the information sought, the footprint values decrease due to scaling.