I would like to export some Org document properties as ODT user defined
fields for use in ODT templates.  For example, it would be great if
something like

#+ODT_FIELD: FOO:17 BAR:"Hello, world!"

in the Org document exported the following user defined fields in the
content.xml.

<text:user-field-decls>
        <text:user-field-decl office:value-type="float" office:value="17"
text:name="FOO"/>
        <text:user-field-decl office:value-type="string"
office:string-value="Hello, world!" text:name="BAR"/>
</text:user-field-decls>

Is this currently possible?

Best Regards,

Kevin