Double logging

I've seen chat as of late about double logging. Would someone kindly define exactly what that is. I've spoken to players who use multiple computers to run their characters. I've heard conflicting theories as to what double logging is and would like it clearly defined.

Simply put,

If you have 2 characters, and you have both characters logged in at the same time, that is double logging.

Double logging is only allowed under strict circumstances.

Please read rule number 5 for full details.
http://www.aranock-online.co.uk/rules.htm

works for me.