The content of containers or the stats of items are set when you run your mouse over it, move it or hit the alt key nearby. If you saved in front of every chest and bookcase in Aleroth, you could re-load and get different items each time. Some containers may have specific items with random stats, some may have a low chance of containing anything, etc but for the most part items are determined as you go through an area.
The list in DDIE shows everything mentioned in the items.000 file. While items in your inventory and chests will be listed, I think it also contains various possible items which may not exist in that particular game.
