... Foundation ¹: This workshop was supported by the National Science Foundation, Information and Data Management Program under the grants IIS-9812229 and IIS-9812230. All opinions, findings, conclusions and recommendations in any material resulting from this workshop are those of the workshop participants and do not pnecessarily reflect the views of the National Science Foundation. Proceedings and the findings of the workshop along with other background resources are made available on the Web (at URLs: http://www.cs.pitt.edu/ $\sim$ panos/idm98 and
http://www.cs.columbia.edu/ $\sim$ klavans/Activities/98-IDM-Workshop/home.html).