Thanks for the response.

As I understand your explanation, it means that for a stereo channel, it will send the left channel only to the L  FX send bus, the right channel only to the R FX send bus.   But what about if the stereo channel, for instance, has reduced or enhanced width set in its control strip?  Likewise, if it is a mono channel, I assume that this means it is fed equally to L and R FX send bus, regardless of the 'pan' setting. 

Mind you, I think this is probably a small issue, because many reverb units work quite well by using a mono input signal to produce a stereo out.

Does this mean that no channel will be sent to the FX send?   If I read your explanation literally, this means that FX send is globally disabled.  Is this what you intended to say?

I have difficulty with the logic of this.  Consider the situation where I have reverb from that channel added to a submix which is my main output.  I have another submix which is also receiving that channel, for example as a cueing feed, which is independent of the main output and has no reverb added (not needed).    If I fade that channel in the main mix to zero, I will still hear its reverbed output in the main channel feed, because the fader is still up in the cueing feed submix.  If the reverb is only being used in the main output, the FX send feed should ONLY be taken from the fader setting of that channel in the main output submix, and not according to the fader setting in another submix that is not having reverb applied at the output.

Perhaps there may be other fields of use with which I am not familiar where this approach is useful.   But from my experience, I cannot think of an application where this particular approach would not cause me operational difficulties such as to not use TM FX reverb and instead rely on external facilities.

Like the Trim Gain facility I think if TotalMix FX is to meet its aim of replacing the analog mixing desk, it needs the ability to decide by submix whether a channel is to use the FX send facility or not.

Thanks for the explanation - it is becoming clearer.

If the small fader alone controls the FX send level, does this mean it then is effectively becomes pre-fade from that channel, and changing the big fader of that channel will not change the level of the signal to the FX send.  And the small fader setting will appear the same in that channel no matter which submix is visible?

If this is the case, what I read in the manual did not make this clear to me.

This is merely saying that an analog mixer has a number of auxiliary busses (as per the manual, the equivalent to sub-mixes in TotalMix) which may be prefade for Monitor, post fade for FX, or even on better desks selectable pre-or post fader by channel. Changing a channel's setting on one buss will not change the level on all the other busses/submixes. In other words, one knob per channel per bus, all independent.  At the expense of a whole lot of knobs, the routing is clearly set out in a Cartesian way, and its state is clearly visible at a glance, and is very flexible.  Important in live work, in my experience.

I am mindful of the semantic issues here because common terms are used differently in the two different worlds.   But in the analog world the (post fade FX) submix IS the FX send.  And only one knob per channel controls the level of the FX send.

In TotalMix FX, there appears to be two cases only for a particular channel in a submix which is (let us say) is designated as the main output, and where the Reverb FX is being included:

(1) without the option activated, the reverb send is derived before the channel fader.  This means if that fader is decreased to lower the level of the sound in the output mix, the reverb is not automatically lowered to keep the proportion of direct to reverb sound the same, and the FX send fader has to be adjusted separately;

(2) with the option activated, the reverb is derived after the channel fader, then lowering that fader will produce a corresponding decrease in reverb, as long as that fader is set higher than that channel's fader in any other submix.  If the fader is reduced below the setting of another submix's fader, the reverb send will not further reduce, and reverb level will be controlled by the fader in a submix where reverb may not in fact be used in its output.   In the extreme, that channel may be reduced to zero in the main output, but its reverb may still be heard.   

Neither of these options appear to be optimum, and prone to error in a live situation, compared to the use of a single post fade aux FX send bus on an analog desk.

To perhaps help better understanding, would it be possible to give an example of a foreseen operational situation that the FX send facility as implemented was designed to handle, and led towards the decision to include it in TotalMix in this particular manner?