A jet pump is provided for supplying fuel from a fuel tank into a sub-tank, which is accommodated in the fuel tank. The hierarchical structure of the XML document is saved separately in an XML skeleton object from which element data other than primary key values has been removed. The object is either removed from the tray by pivoting the carrier about the respective pivot axis, whereby the object slides off the tray in a first direction, or the tray and the object are jointly removed from the carrier by moving the tray and the object in a second direction transversely to said first direction.