These controls are activated with the Simplified Frequency Selection option in the main menu of the voice editor.
These controls give you a complete catalog of what frequencies are available for the TX81Z's operators. There are 992 possible frequency ratios and 1984 possible fixed frequencies that you can set, in case you were wondering.
The frequencies are sorted and I didn't prune out the duplicate frequencies, so there are quite a few duplicates in the list. The duplicates are actually slightly different, though, and these slight differences can have a noticable effect if you're using them for detuning, so I figured I'd better not take them out.
You might also notice that some of the frequencies are out of order in the list. This because I sorted them by sampling the frequencies and comparing them to one another. As it turned out, most of the frequency settings are not what they appear to be in the display. For example, frequency ratio 2.99 is a little higher than 3.00. I'm not sure if this is particular to my unit or applicable to all TX81Zs, so I just went by the information I have. I also only sampled them at A440, so that could affect it, too. My guess is that the relationships between the different frequencies probably change over the range of the keyboard but I only had so much time to figure out the proper order, so you'll have to forgive me for any discrepencies you may find in the order.