The RDA scope document defines some basic concepts that presumably will be used throughout RDA. Some of these concepts it takes from the Dublin Core Abstract Model. In particular, it uses "literal value surrogate" and "non-literal value surrogate." These are defined in footnotes of the scope document as:
The term literal value surrogate is used as defined in the DCMI Abstract Model: “a value surrogate for a literal value, made up of exactly one value string (a literal that encodes the value)”.
The term non-literal value surrogate is used as defined in the DCMI Abstract Model: “a value surrogate for a non-literal value, made up of a property URI (a URI that identifies a property), zero or one value URI (a URI that identifies the non-literal value associated with the property), zero or one vocabulary encoding scheme URI (a URI that identifies the vocabulary encoding scheme of which the value is a member), zero or more value strings (literals that represent the value)”.
I found a more concise definition of this in a PPT by Lutz Maicher, University of Leipzig:
- a resource which is a non-literal value is represented by a proxy
- a resource which is a literal value is represented as literal
In the above, "literal" means a text string. So "Melville, Herman" is a literal, while "http://www.loc.gov/names/#n_79006936" is a non-literal proxy (because it points to the authority record, which is where the actual value is held).
The scope document then states:
- A label is represented by a literal value surrogate.
- A quantity is represented by a non-literal value surrogate
- A quality is represented by a non-literal value surrogate.
- A type is represented by a non-literal value surrogate
- A role is represented by a non-literal value surrogate.
However, in the element analysis in the scope document, it shows that quantities can be represented identically to labels (and I suspect that all other data types can as well). So that document has (and here there is a diagram that I cannot reproduce in email):
[resourceURIref] -> rda:title_proper -> [plain value string]
[resourceURIref] -> rda:extent -> [typed value string]^^[syntax encoding scheme]
- or -
[resourceURIref] -> rda:non_linear_scale -> [plain value string]
Given that the label example and the second example under quantity are structurally the same, I don't see how one can be a literal and one a non-literal.
I see two possibilities here. One is that all of the above has no real effect on the development of RDA, and therefore any errors in interpretation of the DCMI model can be ignored. The other is that the misunderstanding (which I think it is, but wait to be proven wrong) is significant, and therefore needs to be corrected as part of the development of RDA.
My gut feeling is that it is the former -- I don't see references to these definitions in the RDA text itself, and all values are treated as simple value strings. For example, dates are just text:
Record the date of the expression by giving the year or years alone.
1940 (p. 6-47 5rda_sec2349.pdf)
And quantities also seem to be just text strings as well:
12 cm (from 5rda-parta-ch3rev.pdf)
Thus, at least as far as the RDA text is concerned, there are only literal values.
If this is not the case, would some please present the argument for a different understanding. Thank you.