An apparatus and method for determining a target-to-surface distance between a target region in a body and an actual point of entry of a radiation beam into the body from a radiation source. Each of the top-level decode signals has a range of control which is substantially less than the extent of the intermediate nodes. Accordingly, support of mathematical functions can be accomplished among Java objects, one Java object can call another Java object, and the amount of data downloaded from a web server and downloading time can be reduced. The tunable ridged waveguide filter may be formed from two or more ridged-waveguide resonators and may include an RF Input and RF output connected to the resonator and may be direct coupling probes that are either electric or magnetic. The body portion is provided with means to facilitate conversion between a plurality of measurement systemspreferably the more commonly used golf measurement systems of yards or meters, although other distance units and other measurement systems could be included or substituted within the teachings of the invention. A wedge-shaped prying tool in the prying end penetrates the split in the shot and pries it open, releasing the line.