FOLIO Holdings records include a Holdings statement field where libraries can store summary holdings data for serials, journals and/or multi-volume sets. For example, a library may enter something like v.1-25 (1971-1995) in the field. Having this data returned in the z39.50 XML can benefit libraries by allowing ILL staff to quickly determine if they hold the required volume for a journal article request. For example, if the library receives a request for an article from v. 32 of this example journal, ILL staff will know they do not have it and can move on to the next request. 

Scanning lists of items is a workaround but for larger libraries and consortia, the item lists for a particular journal can run quite long and my not be in any sensible order, resulting in more staff time determining whether to process or skip a specific request. 

I am not sure how this could technically be enabled for the FOLIO z39.50 service but the z39.50 service for Sierra, our former ILS places the equivalent data element into the <holding> <publicNote> XML tag. Example: 

 
    <holding>
      <localLocation>UMKC DEPOSITORY</localLocation>
      <callNumber>Periodical </callNumber>
      <publicNote>v.1-95(1932-1979)</publicNote>
    </holding>