852 1st Indicator 2 - National Library of Medicine classification:

Value 2 indicates that the item is shelved by a National Library of Medicine classification number. This number, which is contained in subfield $h (Classification part), has been assigned from the National Library of Medicine Classification schedules QS-QZ and W or from the Library of Congress Classification schedules used by the National Library of Medicine. The National Library of Medicine maintains the National Library of Medicines Schedules. A full description of a National Library of Medicine classification number is given under field 060 (National Library of Medicine Call Number).