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Open discussion of RDA, RDA Toolkit, and related topics
  • 1.  Possible to express relationship to Nomen resource using RDA/RDF properties with no range?

    Posted Nov 18, 2021 05:21 PM

    Hello all: 

    A group of colleagues and I were looking at the RDA element "has series statement" [Toolkit link] recently. We were considering using this element in a linked-data implementation. An initial question was, "Would the value of this element (in an LD implementation, the object of a triple with rdam:P30106 as predicate) be a resource typed as rdac:Nomen? Looking at [Recording methods], and considering a series statement which is a string-structured or unstructured-we saw the following statements:

    • "a structured description of an RDA Entity is a string that is a kind of Nomen"
    • "an unstructured description of an RDA Entity is a string that is a kind of Nomen"
     Based on this, it seemed to us that a linked-data implementation of "(has) series statement" might look something like the following (Turtle syntax; use of blank node versus IRI as Nomen resource is somewhat arbitrary):

    <> a rdac:C10007 ; # Manifestation
    rdam:P30106 _:01 . # series statement
    _:01 a rdac:C10012 ; # Nomen
    rdan:80068 "[series statement string]" . # Nomen string

     BUT there are a few details which make me wonder if such an implementation would actually be correct, in terms of the RDA/RDF ontology, intended use of RDA/RDF properties, etc.

     One is the fact that rdam:P30106 has no rdfs:range.

    Another is the fact that Toolkit guidance for series statement includes…

    "Recording an IRI
    This recording method is not applicable to this element."

    …which would seem to me to indicate that the element (the RDF property rdam:P30106) should not be used to express a relationship between a resource which has rdf:type Manifestation and one which has rdf:type Nomen.

    Any thoughts on whether use of rdam:P30106 as per the above code snippet would be "correct"? Thanks all!


    Benjamin Riesenberg

    Benjamin Riesenberg
    Metadata Librarian
    University of Washington

  • 2.  RE: Possible to express relationship to Nomen resource using RDA/RDF properties with no range?

    Posted Nov 19, 2021 04:22 AM
    Benjamin and colleagues

    The Recording methods guidance sets the context: the methods are for recording "the data value of an RDA element".

    The specific guidance "An unstructured description of an RDA entity is a string that is a kind of Nomen" refers to a string that references an instance of an entity as a whole, rather than one of the elements used in the metadata description set for the instance. This is reinforced by the definition of Nomen as "a label for any RDA entity except a nomen". In other words, such a string or label is an appellation for the instance, and strictly speaking the string is the data value of an appellation element for the instance of the entity.

    There is fuller guidance on the association of recording methods for an entity and appellations/nomens of the entity in Recording methods and nomens.

    That guidance includes the two basic options for recording a nomen string or a nomen IRI as the value of an appellation element.

    These options align with linked data implementations that use OWL datatype elements (nomen string) and object elements (nomen IRI).

    <> # IRI of instance of manifestation
    rdam:P30277 "Appellation string" ; # statement 1: manifestation has appellation that is a string
    rdam:P30277 nomen1 . # statement 2: manifestation has appellation that is a nomen
    nomen1 rdan:P80068 "Appellation string" . # statement 3: the instance of nomen has nomen string (i.e. an appellation that is a string)

    In an OWL implementations, rdam:P30277 can be replaced with rdamd:P30277 (element as datatype) in statement 1, and with rdamo:P30277 (element as object) in statement 2. This is optional; the canonical element rdam:P30277 is often good enough.

    Note that it is not necessary to declare that an instance is of a specific entity; the domain of the element already makes that statement.

    Blank nodes can and should be entirely avoided in well-formed RDA. If an implementation only needs to record nomen strings, the approach used in statement 1 is just fine. The approach used in statement 2 + statement 3 is functionally equivalent, but the cost of creating a metadata description set for an instance of nomen is usually not justified outside of authority control.

    rdam:P30106 is an element subtype of rdam:P30292 ("manifestation statement"). It has no range because the value is always an unstructured description string that is transcribed from a manifestation that is being described. A manifestation statement is not an appellation of the instance of manifestation, and the string is not a nomen string.

    Correct usage is:

    <> rdam:P30106 "Series statement string" .

    Gordon Dunsire