Homework / test German to English Law/Patents Law: Contract(s) Terms and Conditions

Hello everyone,

This term comes from the following sentence:

"Der Käufer darf die Ware Dritter weder verpfänden noch zur Sicherheit übereignen und hat Vollstreckungsmaßnahmen oder jeglichen sonstigen Zugriff auf das Vorbehaltseigentum unverzüglich anzuzeigen".

So far I have:
The Buyer may neither pledge the goods to a third party nor transfer by way of security and has enforcement measures or any other access ???

As you can see, I'm having difficulty with this sentence in general, esp. after "transfer". But perhaps if I can get the meaning of "Vorbehaltseigentum" I will figure the rest out :O)

TIA!