Note 1 to entry: The beams can be formed by electronic scanning or digital array processing.

Note 2 to entry: Strictly speaking, a split-beam echo sounder is a multibeam sonar that forms three or four non-aligned, or oblique, receive beams. Usually these are formed, i.e. processed, internally only.

Note 3 to entry: A particular multibeam sonar can be used for imaging (including measurement of bathymetry), or for measurement of backscattering, and occasionally for both. Internal processing of the received signals depends on the use. A multibeam sonar that is designed for imaging might not support quantitative use, whereas a multibeam sonar that is designed for measurement can support both imaging and quantitative use. However, the multibeam sonar that is designed for measurement will in general have a smaller sampling volume than that of a comparable multibeam sonar designed for imaging.

Note 4 to entry: A multibeam sonar that is used for scientific purposes is sometimes called a "scientific multibeam sonar" or "multibeam echo sounder" (MBES).