Dumb-down
The notions of 'simple DC' and 'qualified DC' are widely used within DCMI documentation and discussion fora. This document does not present a definitive view of what these phrases mean because their usage is somewhat variable. However, in general terms, the phrase 'simple DC' is used to refer to DC metadata that only makes use of properties in the Dublin Core Metadata Element Set [DCMES], that does not make any use of encoding schemes, and in which each statement only contains a value string. The phrase 'qualified DC' is used to refer to metadata that makes use of all the features of the abstract model described here.
The process of translating qualified DC into simple DC is normally referred to as 'dumbing-down'. The process of dumbing-down can be separated into three parts: description dumb-down, property dumb-down and value dumb-down. Furthermore, each of these processes can be approached in one of two ways. Informed dumb-down takes place where the software performing the dumb-down algorithm has knowledge built into it about the descriptions, properties and values being used within a specific DCMI metadata application. Uninformed dumb-down takes place where the software performing the dumb-down algorithm has no prior knowledge about the descriptions, properties and values being used.
Based on this analysis, it is possible to outline a 'dumb-down algorithm' matrix, shown below:
| Description dumb-down | Element dumb-down | Value dumb-down | |
| Uninformed | Generate a separate simple DC description set for each description in the qualified DC description set. | Discard any statement in which the property URI identifies a property that isn't in the Dublin Core Metadata Element Set [DCMES]. | Use value URI (if present) or value string as new value string. Discard any rich representations. Discard any encoding scheme URIs. In cases where no value URI or value string can be determined, discard the statement. |
| Informed | Generate a separate simple DC description set for each of the key entities in the qualified DC description set, as defined by the DCMI metadata application. | Recursively resolve sub-property relationships until a recognised property is reached and substitute the property URI of that property for the existing property URI in the statement. If no recognised property is reached, then discard the statement. (In many cases, this process stops when a property is reached that is not an element refinement.) | Use knowledge of any rich representations, separate descriptions or the value string to create a new value string. |
Note that software should make use of the DCMI term declarations represented in RDF schema language [DC-RDFS], the DC XML namespace URIs [DC-NAMESPACES] and the appropriate DCMI encoding guidelines (XHTML meta tags, XML, RDF/XML, etc.) [DCMI-ENCODINGS] to automate the resolution of sub-property relationships.
In cases where software is dumbing-down a description set containing multiple descriptions, it may either generate several 'simpler' descriptions (one per description in the original description set) or a single 'simple' description (in which case it will have to determine which is the 'primary' description in the original description set). This is an application-specific decision.