I've already surmised what this means from reading the DMG and module G3, but now I've finally located the source! While reading through Eldritch Wizardry (an OD&D supplement), I stumbled upon the confusing "when things happen in a melee round" section. Also in this section were the terms SURPRISE and COMPLETE SURPRISE, and the definition of what these terms meant!!!! I knew that it had to be explained somewhere....
In short, surprise occurs on a roll of 1 (meaning surprise lasts 1 segment) and complete surprise occurs on a roll of 2 (meaning surprise lasts 2 segments). A surprised target thus takes either 1 full round of attacks, or 2 full rounds of attacks without being able to retaliate, run, or otherwise do anything. Curiously, it notes that some creatures and rangers are able to reduce complete surprise to normal surprise, thus only reducing the amount of surprise to 1 segment (but keeping the range of surprise the same, at 2 in 6). This is counterintuitive to what is explained in the DMG....
I think that the oversight of leaving this out of the DMG has caused much more confusion than anything else. Again, the vast majority of players are assumed to have been playing D&D from the start and evolving along with the game. Those of us who joined in the age of AD&D never even knew there was anything before the hardcovers, so we were ignorant as to what was published before. None of these nuances would ever have been known unless one did their research and acquired the out-of-print materials on which AD&D was based. The editors of the DMG did us all a great disservice by not including much of the material seen as being either too complicated or discretionary. I would like to have seen the LBBs and the supplements reprinted in the back of the DMG as historical references, perhaps with fewer illustrations and corrected text. I find myself drawn more and more to the original material, but the only material I can acquire on my budget are incomplete .pdf copies of later printings. My Companion D&D supplement is coming along nicely with all the material left out of the B/X rulebooks from OD&D. I am attempting to keep the flavor of the rules with additions of spells, magic items, perhaps subclasses and some mechanics. I'm also rewriting a lot of the original pastel modules to be compatible with B/X D&D while keeping everything Greyhawk based. I think that the surprise and complete surprise options are a bit too AD&D in flavor, but I will see if they can be incorporated as perhaps an alternate, more simplistic AD&D combat option for those who want more options but less fidgety rules.
