In asynchronous transfer mode (ATM), the average time it takes a cell to transverse the network, from source to destination between a user network interface (UNI) at each end. CTD is the sum of all delays imposed by coding and decoding, segmentation and reassembly (SAR), propagation across transmission media, cell processing at the nodes, queuing of the cell in input and output buffers, and loss and recovery. If a cell arrives too late at the receiving station, it may be considered lost or late, and may be disregarded. If the subject cell is a segment of a larger data packet, the entire packet must be discarded and forgotten, or retransmitted. Maximum CTD (maxCTD) is negotiated between the end stations and the network. See also ATM, buffer, cell, code, network, node, packet, propagation, SAR, and UNI.