Representative Expressions and Representative Expression Elements

A representative expression is an actual or hypothetical expression possessing characteristics that, while techincally belonging to the Expression entity, are perceived as being essential to the identification or characterization of a work. Representative expression elements are RDA elements belonging to the Work entity that document the expression characteristics deemed to represent an "original" or "canonical" realization of a work.

The Library Reference Model1 introduced the concept of the representative expression attribute, from which RDA's representative expression elements are derived.

Definition: An attribute which is deemed essential in characterizing the work and whose values are taken from a representative or canonical expression of the work.
Scope notes: ...The values of these attributes are inferred either from particular expressions considered to best represent the work, or from characteristics abstracted from a more or less nebulous network of similar expressions. There is no requirement to precisely identify an expression or expressions which serves as source for the values of the representative expression attributes, nor does that expression need to be recorded in the case where it is identified.

For much of Western art music, which tends to focus attention on the work and its creator(s), the notion of declaring any particular expression a representative expression is fraught. In this context, representative expressions are best thought of, and less problematic, if viewed through the "nebulous network of similar expressions" model; any expression may be considered representative so long as it shares essential characteristics (representative expression elements) common to many "original or canonical realization[s] of a work," as RDA puts it. RDA does not require that a representative expression exist to be treated as representative; in other words, it may represent a hypothetical ideal.

However, much modern popular music evolved and spread in tandem with recording technology, to the extent that specific recorded performances (usually the first issued) are often considered "definitive" in ways that recordings of art music generally are not. It is much easier to consider a particular performance of a popular song or a particular aggregation of performances in an album to be "an original or canonical realization of a work."

For music that does not fit cleanly into or clearly parallel either category, cataloger's judgment is required. In general, consider how definitive a given expression could or would be in the context of that particular musical tradition and whether users are more likely to approach the find and identify LRM user tasks at the work or expression level.

Treatment of Representative Expressions

General Remarks

It is often unnecessary, and may in some cases be undesirable, to specifically identify an individual expression as a representative expression. In the MARC bibliographic environment, an expression that broadly meets the critieria for a representative expression may be treated as synonymous with the work for most relevant purposes, e.g., preferred titles and authorized access points.2

Do not record structured descriptions, identifiers, or IRIs for representative expression elements as independent elements in MARC bibliographic records for manifestations, regardless of whether or not the specific expression values manifested in the resource cataloged match a representative expression value. Record structured descriptions, identifiers, or IRIs for representative expression elements independently only in authority records for works.

Note: Exception: Identifiers for values of Work: language of representative expression may be recorded in MARC field 041's subfields for original language(s) if deemed useful.

Record unstructured descriptions pertaining to representative expression elements if deemed useful (e.g., "Originally for flute and orchestra, arranged for flute and piano.")

Example: key of expression

  • Title proper of manifestation: Sonata for piano in C major
  • Key of representative expression: C major
  • Element recorded in bibliographic record: Expression: key of expression
    • Not: Work: key of representative expression

Western Art Music and Similar Traditions

For Western art music or other musical traditions where most users, for most purposes, are concerned foremost with access to works and creators of works, in most cases consider that an expression broadly meets the criteria for being representative as long as it does not fall into any of the following categories:

  • Arrangements, including vocal scores and chorus scores
    Note: Follow LC-PCC PS for Expression: designation of version in deciding what does or does not constitute an arrangement
  • Sketches, early drafts, etc.
  • Translations into a language other than the original
  • Other adaptations or alterations that change the genre, style, harmony, texture, etc. in ways significant enough to raise questions as to whether they may potentially constitute a new derivative work (see Work. Entity boundary)

Put another way, generally consider an expression representative if values for Work: medium of performance of musical content of representative expression, Work: key of representative expression (except as noted below), and Work: language of representative expression conform to "original or canonical" values (bearing in mind that, in some cases, multiple values may be "canonical") and no value of Expression: designation of version deviates significantly from what might reasonably be assumed to be the creator's original intent.

In most cases, do not consider the following when deciding if an expression is broadly representative:
  • Expression: content type (that is, notated music or performed music)
    Note: Exceptional cases might include, e.g., a notated music transcription of a work composed by directly manipulating audio samples, magnetic tape, etc.
  • Expression: creator agent of expression (or narrower elements)
  • Transposition of key for vocal music, so long as no other alterations have been made to the original music
  • Added instrumental accompaniment, so long as no alteration has been made to the original music

Modern Popular Music and Similar Traditions

Note: The contents of this section are tentative and may change in future revisions.

For popular music of the 20th and 21st centuries, specific recorded expressions of performed music (often studio recordings, sometimes pieced together from multiple takes) may generally be perceived as the "original" or "canonical" expression of a musical work. The creator of the "canonical" expression may differ from the creator of the musical work. For example, the creator of the work "Never Gonna Give You Up" is the songwriting team Stock Aitken Waterman (or SAW). However, the work is almost universally known to the public via the expression recorded in 1986 by singer Rick Astley; in referring to any other performance, whether by a different agent or even by Astley himself, it would most likely have to be explicitly described to avoid misunderstanding. In this situation, we should likely consider that Astley's 1986 performance constitutes a "canonical" expression of the work.

Possible signs that a specific recorded expression constitutes a representative expression of a musical work may include:

  • The same expression of performed music is embodied in numerous manifestations, with or without augmenting content such as alternate takes, alternative live or studio performances, remixes, instrumental versions, etc.
  • Discussions of a musical work in music journalism, scholarly literature, etc., explicitly reference the same recorded expression, or assume it unless explicitly stated otherwise.
  • The same expression of performed music is frequently used as the basis for derivative works or expressions through sampling, remixing, quotation, etc.

A compilation of recorded expressions (that is, an album) may collectively constitute the representative expression of an aggregating work. See Authorized Access Points for Aggregating Works and Expressions for guidance on providing collective access to albums.

Other Cases

If the music described does not fit neatly into either paradigm described above, apply cataloger's judgment in deciding whether the musical tradition represented is primarily work-focused, and therefore closer to the Western art music model, or primarily expression-focused, and therefore closer to the modern popular music model.

1 IFLA Library Reference Model: A Conceptual Model for Bibliographic Information. January 2018.
2 See the narrative LC-PCC Metadata Guidance Documentation for Aggregates (under Collection Aggregate. Access to Content) and the LC-PCC Expression Metadata Guidance Documentation for Authorized access point for expression: Additional elements and designations.