FIELD DEFINITION AND SCOPE
Information needed to locate and access an electronic resource. The field may be used in a bibliographic record for a resource when that resource or a subset of it is available electronically. In addition, it may be used to locate and access an electronic version of a non-electronic resource described in the bibliographic record or a related electronic resource.
See the Guidelines for the Use of Field 856 for a more thorough discussion on the use of field 856.
Field 856 is repeated when the location data elements vary (the URL in subfield $u or subfields $a, $b, $d, when used). It is also repeated when more than one access method is used, different portions of the item are available electronically, mirror sites are recorded, different formats/resolutions with different URLs are indicated, and related items are recorded.