Note: This is the first of occasional postings involving issues relating to the experimental XOBIS information schema. Such issues stem from our alpha release and current efforts to map MARC to XOBIS. Each issue expands upon or extends topics covered in the general documentation found at: http://xobis.stanford.edu. These explorations will also be useful in identifying any revisions needed for a beta version of XOBIS.
Naming Works
Each Principal Element (PE) in XOBIS contains by an Entry representing a specific named entity. Nine of the PEs may have a Name element to provide identity within the Entry container. However, the name of the PE Work is Title or, in some cases, two or more TitleSegment elements to accommodate section titles and subtitles that are considered part of the Entry. This arrangement suffices until different works occur with the same Title. A small amount of duplication would not be problematic in retrieval, as differences would be manifest in details of the record. With increasing scale, however, too many works could have identical Title elements.
Qualification
To address the duplication of entries, XOBIS posits routine qualification of Title. A Qualifiers element permits disambiguation by serving as a container for entries or substitutes representing one or more Principal Elements. Each qualifier named after its parallel Principal Element consists of the PE Entry with an optional id attribute and an optional substitute attribute that allows specified substitutions in place of it, e.g. Abbrev or Code. This essentially brings qualifiers under "authority" control in that they are equivalent to Principal Elements; should the value of the Entry for a Principal Element change, propagating the change in Qualifiers and Relationships becomes a relatively easy task. However, Qualifiers do not have to be "established" for use in qualification. Ideally, each qualifier would be reflected in another record, but this is not required. Unestablished Qualifiers, those without an id attribute, could be reviewed periodically to determine whether new values need to be established. Note that qualification is only necessary when identical values of the same Principal Element occur because PEs serve as implicit qualifiers (automatic disambiguation).
Enumeration and Chronology
Two kinds of qualification naturally suggest themselves for Title: 1. Numeric sequence (e.g. edition) encompassed by the PE String, and, 2. Chronological sequence (e.g. year) covered under the PE Time. Routine inclusion of these two Qualifiers in an Entry as available should reduce the task of title disambiguation to a manageable level. Both may be recorded descriptively; however, normalization of values used in qualification will benefit indexing and display. E.g. "3rd ed." and "2003" suffice for "3rd rev. & augm. ed." and "c2003" unless needed for further disambiguation. Other Principal Elements may be used as needed for qualification. Any combination of qualifier elements is technically permissible. The PE String permits using any word or phrase in this capacity when other PEs are not suitable. Of course, rules for qualification should be established, preferably as part of an international cataloging code.
General Applicability
XOBIS' single, flexible mechanism for qualification is the vehicle for creating unique entries for any Principal Element. For Work in particular, it extends existing qualification practice, restricted to serial titles and certain uniform titles for choreographic works, motion pictures, etc. In addition, a unique Entry for title eliminates the need for author/title precoordination, which introduces problems when decomposed for indexing. Each Principal Element carries a single identity via its Entry, and as many additional ones as required via Varia (each Variant element is similar to MARC 246). Varia are used generically across all Principal Elements.
Title "Main Entry"
The Entry element for Work serves in effect as "main entry" under title. Some other aspects of XOBIS are relevant:
Examples
Currently, the following 5 serials have the uniform titles shown. Note that date is not routinely included and, when present, consists only of the initial date. Place qualifiers are additionally qualified by place, although punctuation varies from the authorized entry, e.g. Boston (Mass.)
Considering date as a routine qualifier (and date range more informative than start date), these might make better entries in XOBIS. Qualifiers are Duration (Time-Time) and Place, sub-qualified by the Abbrev substitute for another Place. Stylesheets handle the variation in punctuation by context.
However, inclusion of a form qualifier (Concept) may group records by form for improved organization.
Multiple versions present additional challenges. Using a single record for two or more versions could result in entries like those below where Print/Digital could represent a Concept. These qualifiers seem excessive and date range is arguably better than place that may change over the life of a work.
XOBIS offers further flexibility in that the Name element of each Version can carry needed distinctions in the same record. Of course, how Version displays in relationship to Entry is software and stylesheet dependent.
The general issue is mostly one of how to subarrange a group of titles in an index. Similarly, Qualifiers distinguish titles in retrieval lists. Such qualification would only be necessary when titles are ambiguous. Cf. examples from current practice:
Larger Scale Example
The following example indicates various variant entries, authorities, etc. and assumes that display software could support hierarchical features as a result of the information being structured. First, four separate Work records are sketched with Entry and some related attributes and elements to indicate information available for a title index. The first two indicate that they function only as references. Similar records would likely occur for other related titles, although authorities are not required.
The following list indicates how these might appear in a title browse display. Indention in selected cases indicates how "drilling down" or "opening up" the single authority Entry above could only display entries lower in the hierarchy when requested, probably by using an arrow to indicate substructure is present. When an authority record is present, the full browsable substructure should be displayable from any of the Varia. Only some of the cross references and subordinate possibilities are included. Subordinate entries could also display in reverse chronological order. Authority records are only likely when the number of editions becomes problematic.
These examples are based on the occurrence of these titles in Lane Medical Library's catalog. Fairly simple disambiguation handled all the extant cases. This encourages us to believe that title displays could be more effective and that authority effort only need be expended in areas of the file where entries need clarification. We are interested in whether XOBIS' disambiguation mechanism will work with larger numbers of ambiguous titles.
Dick R. Miller
2003-04-11