An antenna 3 of an electromagnetic probe used in investigation of geological formations GF surrounding a borehole WBH comprises a conductive base 31 and an antenna element 32. In addition connecting wires leading from said element to the perimeter of the substrate connecting to contact pads leading to a circuit board. The API presents a logical storage model to the data storage application for storing data on one or more storage appliances and accepts first and second plugins coupling first and second storage appliances, respectively, to the API. The sprung sliding action of the two sleeves contributes to comfort and function. The vertical disparity associated with a first optimal cost is assigned to each candidate horizontal disparity, so that the candidate horizontal disparity and the vertical disparity yield a candidate disparity vector.