Unique identifying numbers for each individual item are critical to the cataloging process. For an installation, it is useful to assign a unique number to the work as a whole and to assign a variation of that number to each component. The numbering system should be as simple as possible. A basic numbering system can describe the collection or creator, assign a number, and give details about format or generation. For example, the video triptych Anima (2000) in the Bill Viola collection, which consists of three separate wall-mounted monitors displaying three different video sources, could be numbered like this:

BV-00001 - For the whole work BV-00001-M1 - For each media component BV-00001-M2 - For each media component BV-00001-M3 - For each media component

The various conventions for numbering should be determined in advance, as should conventions for writing out the number (e.g., the use of hyphens, etc.).