True we could do our own lookup table, but then users would have to refer to documentation anyway to see what valid clock rates are. This way plays nicely with the BITMAINtech documentation.

What if there are more hex codes that just aren't documented? And then, when they are revealed, a new build of bfgminer has to be compiled to add them to bfgminer's lookup table to match BITMAINtech's lookup table.

I agree that I'd rather be able to enter a clock rate, I'm just not sure of the cleanest way to do it.