Holding subfields are used with a 970 Holdings Tag to allow you to specify subfields within the holding tags to which your provider adds holdings information.
In the Subfield field, enter your subfield.
The holdings subfields in use by Sitka are:
Now when MARC records for this provider are loaded through Load MARC Order Records the system will use the subfields in the 970 tag to do such things as generate copies on the line items, apply funds, and add in estimated prices.