Subfield code $1 - Real World Object URI  (Appendix A:  Control Subfields)

Subfield $1 contains a URI that identifies a description of an entity, sometimes referred to as a Thing, a Real World Object or RWO, whether actual or conceptual.  When dereferenced, the URI points to a description of that entity.  A URI that identifies a name or label for an entity is contained in $0.

Examples:

500  1#  $aGoings, Mary Seach (Mary E.),$d1916-2015$0http://id.loc.gov/authorities/names/no2016071283$1http://id.loc.gov/rwo/agents/no2016071283

374  ##  $aAstronauts$0http://id.loc.gov/authorities/subjects/sh85008988$1http://dbpedia.org/resource/Astronaut$2lcsh

380  ##  $aHorror films$0http://id.loc.gov/authorities/genreForms/gf2011026321$1http://www.wikidata.org/entity/Q200092$2lcgft

To return:

Use the key.

See also:

Appendix A:  Control Subfields