The Metadata Asset Action Group is concerned with exposing metadata about the digital asset. This group is optional and is only needed if you want to expose richer metadata than DC which is already listed via the getDCRecord action of the Default Action Group. Many systems can support the dissemination of various different metadata formats. This Asset Action provides a means for a system to list the available metadata formats which can be disseminated. DC is considered the minimal level metadata that is required for an asset, and the getDCRecord action is supported in the required Default Action Group, so it is not repeated here. If the only metadata available is DC, then a Metadata Action Group is not necessary, but if the Metadata Action Group is used, the getDCRecord URI must be repeated in this group as either the Source Metadata or one of the Other Metadata formats.
In many systems that support multiple different metadata formats, one of those formats is used as the source from which the other formats are derived. This is often the richest or most granular of the metadata formats. The getSourceMetadata action should point to a dissemination of that metadata format. In some cases there may not be a single metadata record from which the others are derived, in this case the Source Metadata should point to whatever format is considered the preferred descriptive metadata format. The URI should point to the metadata in its raw form as indicated by the given format MIME type. In cases where there are equivalent metadata but in different formats, such as binary MARC versus MARC XML, preference should be given to the XML format as the Source Metadata.
This asset action should point to the complete metadata record rendered as an HTML fragment suitable for use in a larger HTML web page. This will typically be the detailed metadata record for the item intended to occupy a single web page.
This asset action should point to the brief metadata record rendered as an HTML fragment suitable for use in a larger HTML web page. This will typically be the short record view for the item intended to be used in a list of other similarly formatted metadata records, maybe as a search results list.
This Asset Action can be repeated as many times as necessary to list all the other available metadata formats available for the given asset. You must differentiate these different metadata formats by ensuring that the combination of format and label are unique within this action group. The URI should point to the metadata in its raw form as indicated by the given format MIME type.
Currently most metadata formats will just have a MIME type of application/xml or text/xml. However, the Library of Congress will soon register several new MIME types for various different of its metadata formats, such as application/marcxml+xml, application/mods+xml, application/mets+xml, etc. These have not yet been finalized, but it should allow various metadata formats to be more concisely identified by using just the format attribute. However, there will still be the possible problem of differentiating between different versions of the metadata formats. For this reason, we are proposing to add namespace and schema attributes to the Asset Action XML to allow different versions of the same metadata format to be identified.