MOD, S3M, XM, and IT uses different numbers to represent different commands.
JGMOD convert these different commands in to protracker like commands.
Command 0-15 are protracker effects. Others are S3M and XM extended commands.

Below are the list of JGMOD commands supported. As more it is supported
by JGMOD, I will update the list. This is good for my own reference and
maybe to you too.

Command
-------
-2      Note Off (XM)
-1      Note Cut (S3M)
 0      Arpeggio. (MOD, XM)
 1      Pitch slide up. (MOD)
 2      Pitch slide down. (MOD)
 3      Slide to note. (MOD, S3M, XM)
 4      Vibrato. (MOD, S3M)
 5      Slide to note + Volume slide. (MOD)
 6      Vibrato + volume slide. (MOD)
 7      Tremolo. (MOD, XM)
 8      Set panning.  (MOD, XM)
 9      Set sample offset. (MOD, S3M, XM)
10      Volume slide. (MOD)
11      Position Jump. (MOD, S3M, XM)
12      Set Volume. (MOD, XM)
13      Pattern Break. (MOD, S3M, XM)
14      Extended command. See below
15      Set tempo and bpm. (MOD, XM)

// new set of effects for S3M.
16      Set tempo. (S3M)
17      Volume slide. (S3M)
18      Porta Down. (S3M)
19      Porta Up. (S3M)
20      Tremor. (S3M)
21      S3M Arpeggio. (S3M)
22      Vibrato + Volume Slide. (S3M)
23      Portemento to note + volume slide. (S3M)
24      Multi Retrig. (S3M)
25      S3M tremolo. (S3M)
26      Set bpm. (S3M)
27      Fine vibrato. (S3M)
28      Set Global volume. (S3M, XM)
29      Set Panning. (S3M)

// new set of effects for XM
30      Pitch slide up (XM).
31      Pitch slide down (XM).
32      XM Slide to note + Volume slide. (XM)
33      XM Vibrato + Volume slide (XM)
34      XM Volume slide (XM).
35      Global Volume Slide(XM)
36      Key off(XM)
37      Set envelop position(XM)
38      Panning Slide(XM)
39      Extra fine slide up/down (XM)


Extended command
----------------
1       Fine pitch slide up. (MOD)
2       Fine pitch slide down. (MOD)
3       Set glissando. Not supported.
4       Set vibrato waveform. (MOD, S3M)
5       Set finetune. Not supported.
6       Loop pattern. (MOD, S3M, XM)
7       Set tremolo waveform. (MOD, S3M, XM)
8       Set 16 positon panning. (MOD, S3M)
9       Retrigger sample. (MOD, XM)
10      Fine volume slide up. (MOD)
11      Fine volume slide down. (MOD)
12      Cut sample. (MOD, S3M, XM)
13      Delay Sample. (MOD, S3M, XM)
14      Delay pattern. (MOD, S3M, XM)

// new extended effects for S3M and XM
16      Stereo Control (S3M)
17      Fine porta up (XM)
18      Fine porta down (XM)
19      Fine volume slide up (XM)
20      Fine volume slide down (XM)


Volume Colum Effects
--------------------
0x10 to 0x50    Set volume
0x60 to 0x6F    Volume Slide Down
0x70 to 0x7F    Volume Slide Up
0x80 to 0x8F    Fine volume slide down
0x90 to 0x9F    Fine volume slide up
0xA0 to 0xAF    Set vibrato Speed
0xB0 to 0xBF    Vibrato
0xC0 to 0xCF    Set Panning
0xD0 to 0xDF    Panning slide left
0xE0 to 0xEF    Panning slide right
0xF0 to 0xFF    Tone porta

