Contention resolution information RFC2355 extensions (March, 2003, Draft) https://www.ietf.org/proceedings/56/I-D/draft-ietf-tn3270e-extensions-04.txt z/OS® Communications Server Refer to the z/OS® documentation: https://www.ibm.com/docs/en/zos/2.4.0?topic=zos-communications-server and search on the tern SNAEXT. IBM® Communications Server for Linux®, Linux® on zSeries®, AIX®, and Windows® https://www.ibm.com/products/zos-communications-server/resources