[geotk] Metadata / Use of MetadataExtensionInfo

[Emmanuel Blondel]

Dear all,

I'm currently working with the Geotoolkit / metadata, and i'm wondering 
how can i add MetadataExtensionInformation to the ISO19115. I can see 
there is a DefaultMetadataExtensionInfo, but i'm wondering how it can be 
marshalled into XML? Can it be customized with model tags we want? e.g. 
TaxonomicSystem (example given in annex of the ISO19115 specifications). 
Eventually, is there a Java example of how to use MetadataExtension?

Thanks in advance
Emmanuel