This is not-simulationally-weighted chart for generating levelled NPCs with a single die roll, so it's good if you need NPCs fast in the middle of the game--especially if the players are watching.
To generate an NPC, drop a d4 directly onto the chart. Look where it lands: read up to see the NPC's race, read left to see the NPCs class, look at the number on the die to see the NPC's level.
(For some classes, there are additional rolls that can be used to generate class-specific details.)
To generate a whole party of NPCs at speed (a task for which this kind of chart is unusually useful) drop a handful of D4s onto the chart.
To generate a higher-level NPC you can either use a bigger die (note: dice larger than d4s tend to roll and slide a bit and so possibly roll off the chart, though you can put the chart in a box top and roll that way) or you can interpret the d4 as being like: a 1 = PC level minus one, 2= PC level minus two, etc. Or whatever variation on that fits the situation.
p.s. The guy who published Vornheim will yell at me if I do not point out that that fine publication pioneered tables like this and has some in it so, y'know, you should buy it.