Whats the difference between F0005. Document Type "DT" and "DV"

 I know "DT" contains all the Document Type. Is it correct to make this statement that "DV" only contains Document Types associated with A/P? Does Document Type "DV" contain all the A/P Document Types or are their some exceptions. If I want to enter new Document Type for A/P , do I need to enter in both or only entering in "DV" is sufficient or I need to enter in "DT" and system automatically assigns it to "DV".

Thanks

Shabana