Superimposed applications using SPARCE

People often impose new interpretations onto existing information. In the process, they work with information in two layers: a base layer, where the original information resides, and a superimposed layer, where only the new interpretations reside. Abstractions defined in the Superimposed Pluggable Architecture for Contexts and Excerpts (SPARCE) ease communication between the two layers. SPARCE provides three key abstractions for superimposed information management: mark, context, and excerpt. We demonstrate two applications, RIDPad and Schematics Browser, for use in the appeal process of the US Forest Service (USFS).