http://ozreport.com/forum/viewtopic.php?t=27688&start=10

The DHV certification does not belong to the manufacturer, it
belongs to the German DHV approved dealer. The Dealer needs to have all
equipment to overhaul the glider as well (A fully equipped glider manufacturing
facility). Few can afford to be the dealer.

When a glider has a DHV certification, similar gliders sold outside Germany
cannot carry the certification placard. The non German dealer must buy the
certification placard from the German dealer. I think you would find that
technically many of the gliders accepted at Tegelberg are actually technically
not allowed - for example any Moyes gliders not sold or specifically approved by
the German dealer technically don't have a DHV certification (that is how I
understand it).

The DHV is not just protectionist in terms of foreign gliders, its also
protectionist in terms of the dealers that hold the DHV certification. The
German pilots have to buy their gliders from the German dealers, and that is
quite definitely against European free market laws.