The 853/863 (854/864) paired fields should be used for all currently active serials. They should also be used if at all possible when cataloging multi-part titles and dead serials. However, there are times when using these fields within a holdings record can get extremely complex. If this is the case, it is permissible to use the 866 field in their stead. It is up to the cataloger's judgment to decide which fields are better suited to communicate our holdings to the public. If the decision is to use the 866, remember that the fixed fields still need completing for a serial record (i.e. the LDR 06 needs to be a "v" or a "y"; the 008 bytes 06 and 16 need filling in for the serial holdings).
Multi-part items shelved in different locations:
Occasionally a multi-part item will be shelved in two or more locations, e.g., text and atlas shelved separately. Beginning 4/06, we will create separate holdings records for the part(s) in each shelving location, i.e. with a different 852 subfield c or m. The 853/863 and 854/864 fields in each holdings record should reflect only the parts therein. The following example is for a 4-volume text with oversize 2-volume atlas shelved separately:
852 … |c GEN |h Typ 815.26.2570
853 20 |8 1 |a v.
863 40 |8 1.1 |a1-4
852 … |c GEN |cPF |h Typ 815.26.2570
854 03 |8 1 |a (unit) |b v.
864 41 |81.1 |a atlas |b 1-2