SOIRs were re-named 'Land And Hold Short Operations' (LAHSOs) back in 1997. Most non-US operators (including UK) may not use LAHSOs, as their operating authorities are not convinced of the safety of such procedures. Experience at Boston, in particular, suggests they are right to be cautious! However, you may come across them if you are training in the USA on 'N' registered aircraft. If you do, learn all you can before you use them, and keep your wits about you!
Scroggs