AnalogExif allows definition of the custom XMP schema. After schema is defined it is possible to add custom metadata tags that would be stored in the image and shown in some of the photo-related programs and services (for example, Flickr).
The custom XMP schema information is stored in the equipment library. If you define custom XMP schema in one equipment library, custom metadata tags will not be available for edit with another equipment library - you would have to redefine the XMP schema and add corresponding metadata tags.
Define custom XMP schema
Schema namespace is the URL for schema RDF definition. Since most of the XMP parsers do not verify the custom schemas, you can specify "/" as schema namespace. Schema prefix is used when adding new metadata properties. You can reference custom tags as Xmp.<schema prefix>.<tag name>.