This OCTET STRING gives the blade bay number associated with a WWN/GUID table row: for an expansion card it is the bay number of the blade that card plugs into, while for a blade itself it is simply that blade's own bay number. An admin uses it to tie a set of storage-adapter identifiers back to the correct physical blade in a chassis holding several blades, each potentially carrying its own expansion card. For example, a row whose bladeAndExpCardWwnGuidVpdBladeBayNumber reads 4 tells the admin the WWN values in that row belong to hardware associated with the blade seated in bay 4, whether that hardware is the blade itself or a card plugged into it.