So to make a long story short I've been digging through the old books and have bumped into mentions of Semi Autonomous Knowbots (or SAKs) on more than one occasion. They are emphasized to have a very high hacking skill, very high matrix attributes, and can create programs on the fly. Yet we see no mention of them whatsoever after 3rd edition. I'm wondering why? My first assumption was that they just translated into powerful agents, since agents can hold as many programs as they like until they actually run the program. But we also had agents in 3rd edition from what I can tell.
So my big question is what exactly are the differences between SAKs and agents and how would I run them using the 4th edition rules? Would I treat them as high rating (or even rating 7+) agents or are we talking about an entirely different beast here?