X47 Subfield $i - Relationship information: [447, 547, 747]
Subfield $i contains the designation of a relationship of the entity in a 447, 547, or 747 field to the 1XX entity in the record or a textual reference instruction phrase. For fields 447 and 547 the phrase may be system-generated from the field tag or from the codes defined for subfield $w (Control subfield). Subfield $i is appropriate only in fields 447, 547, and 747.
Guidelines for using subfield $i: