IV.10Marine or terrestrial acoustic equipment capable of detecting or locating underwater objects or features or of determining the position of surface vessels or submersible vehicles Note: (i) 6A001.a.1. does not control the following equipment: a. Depth sounders operating vertically below the apparatus, not including a scanning function exceeding ± 20º, and limited to measuring the depth of water, the distance of submerged or buried objects, or fish finding; b. Acoustic beacons, including: - Acoustic emergency beacons; - Pingers specially designed for relocating or returning to an underwater position. (ii) Technical Note: For the purposes of 6A001.a.1.a., enhancement includes the ability to compensate by external means.