The value of comprehensive rationale for documenting
a design has long been recognized. However, designers rarely
produce detailed rationale in practice because of the substantial
time investment required. Efforts to support the acquisition
of rationale information have focused on languages and
tools for structuring the acquisition process, but still
require substantial involvement on the part of the designer.
This paper describes an experimental system, the Rationale
Construction Framework (RCF), that acquires rationale information
for the detailed design process without disrupting a designer's
normal activities. The underlying approach involves monitoring
designer interactions with a commercial computer-assisted
design (CAD) tool to produce a rich process history. This
history is subsequently structured and interpreted relative
to a background theory of design metaphors that
enable explanation of certain aspects of the design process.
The framework provides an environment that can acquire
rich, meaningful rationale information in a time- and cost-effective
manner, with minimal disruption to the designer.