volume policy when unspecified: retrigger (note+inst cmd) -> default value, no retrigger (note cmd only) -> prev value

terranmon.txt

@@ -2339,13 +2339,15 @@ TODO:
         Hz values verbatim (no SLIDE_UNITS_PER_HZ scaling) and sets the
         linear-freq flag in the song-table flags byte. Spec details in
         TAUD_NOTE_EFFECTS.md §1, §E, §F, §G.
-    [ ] milkytracker-style volume ramping (on sample-end only)
+    [x] milkytracker-style volume ramping (on sample-end only)
     [x] make Cues tab move faster
         Resolution: Cues panel now uses memory-shift (`shiftOrdersAreaHorizontal`)
         for LEFT/RIGHT and `shiftPatternArea` for UP/DOWN, plus per-row
         (`drawOrdersRowAt`) and per-column (`drawOrdersVoiceColumnAt`) helpers,
         replacing the full-panel redraw on every keystroke.
     [x] volume and panning policy to match note effect policy: when note is "retriggerred" (note command with instrument specified), the volume/pan must take default value; if not (note command with instrument 0) the volume/pan must stay at the old value. Make both audio engine and taut.js simulator changes.
+    [ ] xm volume column commands (+x, -x, Dx, Lx, Mx, Px, Rx, Sx, Ux, Vx) are completely ignored
+    [ ] theday.xm order 0x28, channel 6..8 has 'note trigger with inst 1 but no volume -> key-off -> set-volume to 0x20 -> key-off -> set-volume to 0x10 -> key-off -> ...' and it sounds like gating: key-off silences the output, set-volume turns on the output again; notably, this behaviour only works when volume envelope is turned off (any fadeouts progress normally). What I want to know before implementing this feature is that would the way it works on XM conflicts with Taud or ImpulseTracker's behaviour
 
 
 Play Data: play data are series of tracker-like instructions, visualised as: