In asynchronous transfer mode (ATM), a dependability parameter expressed as the number of cells received over a time interval at a destination endpoint that were not transmitted originally by the source endpoint of the virtual circuit (VC). CMR is expressed as a rate, rather than as a ratio, because the number of misinserted cells is beyond the control of the originating and destination endpoints. Although the header checksum is designed to prevent misinsertion, CMR can result from the corruption of a cell header, which would cause a cell to be misinserted into the cell stream of another source-destination pair of end points. See also ATM, cell, checksum, endpoint, header, and VC.