A document retrieval system has an index information generator that generates index information about the frequency of occurrence of non-numeric terms in documents, and index information about the numeric values of numeric terms and the types of quantities they represent. The method includes providing a sacrificial material over at least the active area of the non-silicon-based device, depositing a seal coating over the wafer so that the seal coating covers the sacrificial material, and replacing the sacrificial material with a target atmosphere. The front of the backpack is hinged to open an interior area where play toys and accessories can be located to simulate a dollhouse, space vehicle, barn or like play themes. A support is mounted on the support arm. At least one of the catalog item object representations is requested using the corresponding catalog object identifier. Once the playing switches are turned on, the circuit modules will execute a playing procedure whereby the play datum are played by means of a playing unit of the sound-generating devices.