The Overcast (Overlaid Concepts and Structures) project deals with superimposed information: information—placed over base sources—that contains marks that reference useful fragments of base information. Advantages of marking over “copy and paste” include retaining context of marked fragments, using applications associated with the base information to interpret them, and retaining the connection among multiple uses of a base information element.

Overcast will widen the use of superimposed information by (1) enriching base information with superimposed models and behaviors, (2) making marks transferable to other representations of base content, (3) developing rich transformation capabilities over assemblages of superimposed and base information, (4) broadening the situations where superimposed information can be used, and (5) extending architectural capabilities and deployment options. Broader impacts include involvement of PhD, MS and high-school students; integration of results in existing curriculum; strong involvement of women in the project; use of developed technology in education using digital libraries; and helping computer users generally to perform information tasks more effectively, not just more efficiently.