This counts application-layer user messages that SCTP had to split into multiple chunks because they exceeded the path's effective MTU, a direct consequence of the messaging application sending payloads larger than the SCTP layer's fragmentation threshold. A high or rising rate here suggests the application is regularly sending oversized messages relative to the network path, which adds reassembly overhead and, on lossy links, increases the odds that losing just one fragment forces retransmission of the whole message. Tuning the application to keep messages under the path MTU, or increasing PMTU where reachable, would directly reduce this counter's growth.