Determining the "Absolute" Values of Reverb and Chorus

A Performance Preset contains several level/send values for each
patch made from among the following.

1) Patch Tone Reverb and Chorus Send Levels
2) Patch Common Reverb and Chorus Levels 
3) Performance Part Reverb and Chorus Send Levels
4) Performance Reverb and Chorus Levels

And the above is independent of CC91 and CC93 controller data
being sent to a Part's Assigned MIDI Channel to affect Reverb
and Chorus respectively.

When a Performance Part Output Assign is set to PAT (Patch),
stages 1, 2 and 4 apply. When set to MIX, only stages 3-4 apply.
When set to EFX, stages 3-4 AND the Performance EFX Reverb and
Chorus Send levels REPLACE those of stage 3. For JV users, if
OUT1 or OUT2 is used, NONE of the above stages apply. In other
words, in general, a Patch's Levels from stage 1 and 2 are
replaced by those of 3 and 4. [If I am wrong about any of this,
feel free to say so <g>.]

For JV-1080 users, look at page 100 in the Owner's Manual. For
XP-50 users, see page 9 in your manual.

Therefore to determine an "absolute" value used for a Part to
emulate an GM/GS/XG equivalent setting each Ouptut Assign
setting will have a different "formula" to use. For
simplicity's sake, "Level" will be used to refer to either
Reverb or Chorus 0-127 values below.

Since the synth's MASTER values and output are controlled at
stage 4, if they are 0 then the values of the other stages
are irrelavent. These MASTER values are normally set to 64 on
GS and XG compatibles. To avoid needing sysex though allowed
in GS and XG synths, is not in GM Mode, a scaling can be
applied to the data as if the MASTER values were set to 64
such that JV/XP MASTER:GM/GS/XG MASTER as 127:64 (i.e. ":"
means is proportional to or "is to"). In other words the
relationship is "practically" 2 to 1.

The other "submix" values then act as proportions among each
other. For example, consider the following case, from
Performance Preset-A 01: House Set, Part 1, Patch PR-A:007
House Piano, which uses 2 Tones with the following "stage" info:

[RL=reverb level/send, CL=chorus level/send,OA=output assign]
Waveforms                  RL   CL   OA
INT-A:002 (Ac Piano1 B )   100  20   EFX
INT-A:006 (Organ 4     )   100  20   EFX

Patch Common               127  127
Patch EFX Levels            60   50
Performance Part 1         127  127  EFX
Performance EFX Levels      60   50
Performance MASTER Levels  127  127

Since EFX is used in the PERFORM Output Assign of the Patch, the
Tone (and Patch EFX) levels (from stage 1), therefore only the
following need to be considered:

b Performance Part 1         127  127  EFX
a Performance EFX Levels      60   50
  Performance MASTER Levels  127  127

The "absolute" value obtained for Part 1's Reverb therefore
would be derived from MASTER:a:b, i.e. using 100%=127, 64/127 *
60/127 * 127/127 * (the scaling factor) 127, which equals .5 *
.47 * 1 * 127 = 30. If a controller value were used, then it
would be the percentage (of itself divided by 127 * 100) of the
previous result. For example if a CC91 value of 64 were used
then 50% of 30 would obtain 15 as the "absolute" value.

Any comments, criticism, and above all, corrections to the above
would be appreciated.