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# Physical and virtual union catalogs
- URL: https://www.lorcandempsey.net/physical-and-virtual-union-catalogs/
- Published: 2004-06-22T08:40:56.000Z
- Updated: 2004-06-22T08:40:56.000Z
- Author: Lorcan Dempsey
- Tags: Institutions, Systems

[CC-Interop](https://ccinterop.cdlr.strath.ac.uk/?ref=lorcandempsey.net) is a UK project looking at aspects of the interplay between what it calls ‘physical’ union catalogs and ‘virtual’ union catalogs. The latter are z39.50 enabled ‘clumps’ of catalogs.  
It has produced several reports, the most recent of which looks at the use of Collection Level Descriptions to ‘landscape’ an environment of catalogs. \[[pdf](https://ccinterop.cdlr.strath.ac.uk/documents/CLDLandscapingReportMaster1.pdf?ref=lorcandempsey.net)\]