Conspectus is a system used to evaluate the collection of a library. At first it was mostly used by college or university libraries, since it was developed in the early 1980s by the Research Library Group, but later it was adapted to the needs of smaller libraries with software developed by the Western Library Network. It originally took the areas set out in the Library of Congress Classification System (though it can now be used with the Dewey Decimal System) and for each one, would:
  1. Examine the library's collection in that area.
  2. Record the data gathered (number of books, etc.) including any special comments on important or unique characteristics of the collection for that subject.
  3. Use that data to determine the library's current collection level and their acquisition level (if the subject area is being expanded, ignored, or whatever), the collection goal if the current collection is not what it is needed to be, and the preservation commitment (is it important to keep the particular work in its original form, or just to preserve the informational content in any available form?)
  4. Fill out the conspectus worksheets so that the information is all together and can be seen for decision-making purposes (such as budgeting for new acquisitions).
The WLN version of the Conspectus divides all subjects into 24 major Divisions. Divisions are broken down into Categories, of which there are about 500 total, and Categories can be further subdivided into Subjects (about 4,000 total). A library can get worksheets to evaluate on either a Category or a Subject level. For each division (Catgory or Subject) the current collection level, acquisition commitment, collection goal, and preservation goal will be ranked from 0 to 5.
0
Out of scope (the library doesn't feel it needs to have any information in this area)
1
Minimal level (perhaps a few very basic works)
  • 1a - Minimal level, uneven coverage
  • 1b - Minimal level, even coverage: at least a little effort to cover the important aspects has been made.
2
Basic information level - enough for popular interest but not real study
  • 2a - Basic information level, Introductory
  • 2b - Basic information level, Advanced (Appropriate for community college students)
3
Study or instructional support level
  • 3a - Basic study or instructional support level (Adequate to support lower division undergraduate courses)
  • 3b - Intermediate study or instructional support level (Adequate to support upper division undergraduate courses; not adequate for master's degree programs)
  • 3c - Advanced study or instructional support level (Adequate to support master's degree programs)
4
Research level (Adequate to support doctoral research)
5
Comprehensive level (Aiming to have every significant work on the subject)
The WLN Conspectus software includes several databases allowing a library to compare itself to other participating libraries (or the recommended works from reference anthologies) as well as the ability to print out reports for individual library collections. The WLN Collection Assessment Manual also gives instructions for evaluating what level a library collection really is, how to allow for computerized resources, and a lot more information; this manual was the text when I took a course in Collection Assessment when working on my Master's in Library Science.

Sources:
Western Library Network. WLN Collection Assessment Manual, 4th ed. Lacey, Washington: WLN, 1992.
http://www.rlg.org/conspechist.html
http://lib.umflint.edu/consummary.html
http://www.oclc.org/western/products/aca/conspect.htm
http://www.nla.gov.au/niac/conspectus/korea.html
http://www.nla.gov.au/libraries/hosted/wln-cdp.html