Whilst DV supports several hundred different fields, DV can never be all-encompassing.
There are two ways to supply additional fields:
Unsupported properties are fields where both the key and value is determined by the advertiser. DV will not process these fields in any way, other than storing them with the object.
When advertising the object, these fields will be added to the advertisement description using the format "key: value". Advertisements cannot be filtered using these unsupported properties on sites.
Both key and value can be supplied in multiple languages. One can supply an unlimited amount of unsupported properties.
Hexon will periodically check the unsupported properties when determining which fields to add to DV next.
Extra fields support the same purpose as unsupported properties, but these will not be advertised. They are however sent to the website of the advertiser, and can thus be used to send additional or custom data to the website. There currently is a limit of 10 extra fields per object.