The assign mode determines which of the eight possible voices turn on as you play each note. The two possible settings are normal and alternate. When a key is pressed in normal mode, all of the instruments sound off that are on the channel of the note-on message. In alternate mode, all of the notes assigned to a channel act like a chain, and when a key is pressed, only one of the notes in the chain is played. The next key will play the next note in the chain, and this continues until it circles around.
For example, say you have a performance set up like this:
In normal mode, if you were you play the notes C-E-G-B on channel 1, then you would hear voices I01 and I02 for all four notes. In alternate mode, you would hear voice I01 for C-E, and I02 for G-B, because there are two notes assigned to each.
It's kind of a strange feature, but you can do some nifty things with it.
This is where you select the effect you want to use for the performance. These effects are described in the Effects Editor section. Unfortunately, you can only have one of these effects activated at a time.
This is where the microtune table is selected. Don't ask, I have no idea what they are or what properties they have — I just copied the names out of the manual :-)
This is where the microtune key is selected. This only applies to certain microtuning tables: Pure Major, Pure Minor, Mean Tone, and Pythagorean. If this setting doesn't apply to the selected microtuning table, then this control will have asterisk in it to indicate that it has no effect.
These controls are where the individual instruments are edited. An "instrument" is a voice along with some performance parameters. The performance parameters are completely independent of the parameters that are set in the voice editor.
The slider does the same thing, but a little more inconveniently. I originally had the slider by itself with the voice name statically displayed, but I swapped the static display with a menu button and I just left the slider in there. You can type the voice number into the slider and use the other LCD control features, so it's not entirely useless.
The instrument menu button gives you a couple of high level editing operations so you can edit multiple instruments. You can copy one instrument to another or swap two instruments, which is useful when you want to use the LFO of a certain voice and you want to move it to slot 1 or 2. You can also copy an instrument to multiple instruments. When this function is selected, you'll see a dialog box that looks like this:
Just check which instruments you want to copy the settings to and click OK to copy them.
Note the rules for max notes always apply, so pay careful attention when using these functions because it's possible for notes to be robbed from other instruments.