...
When adding, the holdings summary statement (866a) should be updated to reflect the new additions. Generally, the established pattern should be followed, but not if that numbering system can no longer be found on the pieces. Significant numbering changes may require a bibliographic adjustment; refer to a serials cataloger before proceeding.
Many serials have partial holdings in a Recap location, and whether a newer or an older run of volumes has been recapped varies. If unsure where the new item should be added, check the 866 holdings statements for both locations. In general, new units will be added to the location with the most recent holdings.
Note that the data before and after the hyphen need not be perfectly symmetrical. Slight changes over time in the way the publisher has numbered pieces may result in a holdings statement like this:
...