A bus arbitration section and a resource control section are interposed between a shared resource and a plurality of bus masters. When the slip-control is not in progress, if an actual transmission ratio is out of a predetermined range of the target transmission ratio, the abnormality judgment section judges that abnormality occurs. In an aspect, the window is printed with a pattern. However, the inner container includes an enlarged top configured to engage the outer container. A database traversal system and method is provided.