Each Dublin Core metadata field can contain up to 2 GB of data.
Included with the definition of an asset is the metadata used to describe the asset. The metadata is indexed in Portfolio and searched by patrons so they can locate the assets they want.
Metadata for assets can be added or obtained in the following ways.
| • | Manually entered when you create or edit an asset. (See Adding a digital asset for more information.) |
| • | Imported from a file when you create or edit an asset. (See Fields: Add/Edit Asset for more information.) |
| • | Imported in bulk with a DaXML, Dublin Core XML, MARC 21 XML, UNIMARC, or MARC 21 file. (See Importing multiple assets for more information.) |
| • | Harvested from an OAI-PMH site. (See Harvesting assets from OAI-PMH sites for more information.) |
When you add or import an asset, and upload the metadata from a file or a MARC record, the metadata from the uploaded file or MARC record is compared to any existing metadata fields for the asset. All metadata fields from the uploaded file or MARC record are appended to the end of the asset’s metadata list regardless of whether the metadata field or fields are already present in the asset’s metadata list, or not. You may modify the asset if you want to edit all of the metadata for the asset.
Each Dublin Core metadata field can contain up to 2 GB of data.
For example, you decide to create an asset for a sound file, and upload Dublin Core metadata for the asset from an XML file. You specify a title for the asset. The XML file contains metadata for the title and the creator of the asset. Since you manually specified a title for the asset, the title metadata in the XML file will be appended to the end of the existing metadata list when the asset is added or imported into the digital asset hierarchy. The creator metadata from the XML file will also be added to the end of the asset’s metadata list since you did not manually specify creator information for the asset.
As another example, you create an asset and upload a MARC 21 file that contains only metadata for the asset. The MARC 21 file specifies metadata for the title, author, and publication date. At a later time, you edit the asset and attach a PDF file that has metadata for the title and language. Since the asset already contains a title that was added from the MARC 21 record, the title metadata in the PDF file will be appended to the end of the existing metadata list. The language metadata from the PDF file is also appended to the end of the asset’s metadata list since the language metadata did not already exist for the asset.
Metadata templates are useful in ensuring consistent specification of metadata when assets are created, edited, or imported. A metadata template is a selected set of metadata fields for an asset. You can create metadata templates that are as general or as specific as you like. For example, you can create a metadata template that will be used for assets that contain PDF files. The PDF file template contains all of the fields for metadata that you want to include for PDF file assets. (See Managing metadata templates for more information about metadata templates.)
The Dublin Core metadata fields map to search fields in Portfolio to provide the ability for patrons to search for assets using metadata keywords. In addition, these fields can also be used as facets for narrowing a search to a specific type of metadata. (For more information, see Dublin Core metadata field to search field mapping.) You can also map search fields that don't correspond to Dublin Core metadata fields to be used as metadata fields for assets. These metadata fields retain the name of the search fields in your system. The data that you enter is indexed, searched, and displayed as thought they were search fields.
Data in all of the Dublin Core metadata fields can be searched by patron searches.
Since all metadata fields map to existing search fields, some restrictions may exist on how information can be entered into certain metadata fields. For example, for languages to display correctly in assets and search results, the language codes must be entered according to the standard specified in ISO 639-2. (For a list of the ISO 639-2 standard language codes, go to the Library of Congress ISO 639-2 Registration Authority Web page at http://www.loc.gov/standards/iso639-2/.)
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