The present invention relates to an improved endoscopic tissue apposition device having multiple suction ports. The method is characterised in that the separating medium is a ferrofluid, i. After ferroelectric layers are formed over the plurality of wafer substrates, the ferroelectric layers formed are damaged. Because the cluster database provides consistent data to the nodes even in the presence of a failure, each node will have consistent mapping and file permission data. The test pattern detector establishes expected test patterns. If the determined difference is less than a threshold, subsequent columns or rows are determined by previously determined columns or rows.