====== Call Number Fields: Populations and Purposes ======

This is Naomi Dushay's best attempt to understand the call number fields in VuFind as of 2008-08-11.  It is not guaranteed to be correct, nor up to date.  It is shared here in the hopes it  can help others.

^Field Name ^ Function ^ Traits ^ Current Algorithm ^
| **callnumber** | call number Searches \\ \\ Display \\ \\ Sorting Search Results | not tokenized \\ stored \\ indexed \\ not multivalued | take first of 090ab, 050ab \\ \\ (full call number)|
| **callnumber-a** | ? | not tokenized \\ stored \\ indexed \\ not multivalued | take first of 090a, 050a \\ \\ (call number before Cutter) |
| **callnumber-first** | facet | not tokenized \\ stored \\ not multivalued | first letter of callnumber \\ mapped to terse description \\ \\ AJAX.php getNarrowOptions() hardcoded assignment \\ to strings for display |
| **callnumber-subject** | facet   but only after \\ callnumber-first \\ has already been selected | not tokenized \\ stored \\ not multivalued | first letter blob of call number (e.g. "ML" or "PQ") |     
| **callnumber-label** | facet   but only after \\ callnumber-subject \\ has already been selected \\ \\ GetMoreLikeThis query | not tokenized \\ stored \\ not multivalued | unsure |

Note that Stanford will be using multivalued call numbers, as we have many bib records that refer to multiple items with potentially different call numbers.  In addition, for the purposes of browsing by call number as a subject browse, we want to be as inclusive as possible, using call numbers directly associated with our items as well as any relevant call numbers in 050 and 090 fields.