-------- Original Message --------
Subject:        Calculating extent in electronic records
Date:   Thu, 03 Dec 2009 11:55:29 -0700
From:   Elizabeth Perkes <[log in to unmask]>
To:     <[log in to unmask]>



When you produce catalog entries or finding aids for electronic records, what criteria do you use to count the extent (or quantity)?  For instance, we collect geospatial records. The bibliographic record for the series identifies them as municipal boundaries (or whatever). Within that series we have identified 10 years' worth of individual datasets, so each year is a separate entry within our database--including the metadata for that particular year. Within those datasets, we break the numbers down by format (geodatabase, shapefile, PDF, or raster), and within the formats, we again break it down by file size each for compressed and uncompressed versions of the data. Often the geodatabases and shapefiles are only downloadable as .zip files for patron use, but of course when these files are unzipped they have a value, which we are recording.

So the question is, should I just add all the KB/MB/GB/TB together from all the fields and come up with a single number of bytes, or should I separate out the counts for uncompressed bytes and compressed bytes, whether or not we make them available both ways? Not separating them makes me feel like I'm counting apples with oranges, and separating them makes me feel like we are counting the same data twice (as if we have twice as much data as we do). If I just provide the extent for what's downloadable from our FTP server (the zipped value), that does not let the patron know what size ultimately to expect when it is unzipped. Plus, the PDF files are always uncompressed, so we have to display that number somewhere. And if we have this stuff stored on physical media, our database will automatically include the number of cubic feet--duplicating quantity counts yet again. Any thoughts?


Elizabeth Perkes
Electronic Records Archivist
Utah State Archives
346 South Rio Grande
Salt Lake City, UT 84101-1106
801-531-3852
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