2.5B17.

In recording multipart items consisting of numbered and unnumbered volumes (e.g., unnumbered Constitution volume and ... court rules volume constituting part of numbered Revised statutes ... set), record in the extent statement the numbered volumes only. Indicate the total of unnumbered volumes as part of the note accounting for the unnumbered volumes if this is not clear from the note itself.

See also:

2.5B. Number of volumes and/or pagination