Locks the script to only run when bound to localhost (bind 127.0.0.1 in server.cfg). This is good for giving the script to strangers for testing, without them being able to steal it. Uses extremely obfuscated code to stop reverse engineering.
For general YSI information, see the following links:
These are links to external documentation and tutorials; both first- and third-party. Note that these may be incomplete, obsolete, or otherwise inaccurate.