This writable value sets the upper limit on the number of SD (Sequenced Data) PDUs SSCOP may transmit between POLL PDUs, or before the first POLL after the poll timer becomes active. It lets an admin control the trade-off between signaling throughput and how often flow-control status is refreshed via polling. For example, an admin might lower this limit if they want more frequent POLL PDUs to catch sequencing errors sooner on a busy signaling link.