Combat: AUTHENTIC weapon groups -- streamed per-mech button bindings + the real fire chain (task #5)

The recovered system: fire channels = LBE4ControlsManager buttonGroups
(0x40/0x45/0x46/0x47); default groups = the per-mech type-6 controls-map
resource in BTL4.RES, installed by the T0 CreateStreamedMappings the port
already called -- it needed only the TriggerState attribute (id 0x13 PINNED
to the binary value; fireImpulse@0x31C is the binary's TriggerState) and an
input feed.  Keyboard/harness now push press/release edges into the button
groups; the gBT*Trigger bypasses, per-type keyboard split and 1,0 pulse
hack are retired -- weapons sharing a button fire TOGETHER (madcat Trigger
= 4 weapons).  Myomers @4b9550/@4b95b8 misattribution corrected (they are
MechWeapon ConfigureMappables/ChooseButton).  Verified 2-node: kill through
the authentic chain (12 hits vs ~36 pre-groups).  Config-mode session
(regrouping UI) = the remaining stage, KB-scoped.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

context/open-questions.md

@@ -110,16 +110,26 @@ authentic path scoped.
 - **MechControlsMapper look/eyepoint commit** — reconstructed but its offsets collide with declared
   members; arbitrate before enabling (no port consumer yet). The fire-trigger-through-mapper is
   still the `gBTWeaponTrigger` bring-up.
-- **Weapon groups / per-button fire channels (decomp-anchored 2026-07-09)** — MechWeapon message
-  handlers id 9 **`ConfigureMappables`** (`FUN_004b9550`) and id 10 **`ChooseButton`**
-  (`FUN_004b95b8`), table @0x511860 region: ConfigureMappables binds the weapon's
-  `fireImpulse`@0x31C to mapper fire-channel #N (msg value 1-based; <1 unbinds; mapper = roster
-  slot 0, vtable +0x38 register / +0x3c unregister; weapon+0x110 = the bound-state), ChooseButton
-  re-binds (vtable +0x44) — the pod's in-cockpit weapon→button GROUPING. Weapons sharing a button
-  fire together; grouping was a PILOT choice (heat management: alpha vs split). The port's
-  SPACE=all-energy / CTRL=missiles split is a stand-in default; the authentic system needs the
-  mapper channel registration + who SENDS the default ConfigureMappables (mission/player setup —
-  not yet traced). Payoff: authentic weapon groups + a path to chain-fire.
+- **✅ Weapon groups — the AUTHENTIC defaults + fire path LIVE (task #5, 2026-07-11) [T1/T2].**
+  The system decoded end-to-end: a fire "channel" = a physical `buttonGroup` slot in the global
+  `LBE4ControlsManager` (fire buttons 0x40 Trigger / 0x45 Pinky / 0x46 ThumbLow / 0x47 ThumbHigh);
+  binding = a permanent mode-0x10000 DIRECT mapping button → the weapon's **TriggerState** attr
+  (id **0x13**, = `fireImpulse@0x31C`; the binary MechWeapon table's ONLY attribute @0x511890);
+  the weapon self-edge-detects (CheckFireEdge @4b9608).  **The default grouping is NOT messages —
+  it is the per-mech type-6 controls-map resource in BTL4.RES** ("Thrustmaster"/"L4" variants;
+  e.g. madcat: Trigger={4 weapons}, ThumbHigh={2}), installed at `MakeViewpointEntity` by the
+  ENGINE's `CreateStreamedMappings` (T0, L4CTRL.cpp) — which the port already called; it needed
+  only the TriggerState attribute published (id PINNED to 0x13 — our attr-id chain is 6 short of
+  the binary's; full binary attr-table dump in the task #5 scan) + an input feed.  Keyboard now
+  pushes press/release edges into the buttonGroups (SPACE→Trigger, '2'→ThumbLow, '3'/CTRL→
+  ThumbHigh; BT_AUTOFIRE pulses the Trigger); the gBT*Trigger bypasses + pulse hack are retired.
+  VERIFIED 2-node: full kill through the authentic chain (12 hits vs ~36 pre-groups = the
+  4-weapon trigger volley + crit cascade).  **Remaining (the config-mode session):** handlers
+  id 9/10 (@4b9550/@4b95b8 — corrected: they were mislabeled as Myomers fns), the L4 mapper
+  Enter/ExitConfiguration completion (StartMappableButtonsConfigure + mode 0x8000), the
+  ConfigMapGauge unguard — the pod's in-cockpit REGROUPING UI (pilot heat-management choice);
+  mapper vtable corrections: +0x38 Enter / +0x3c Exit / +0x44 RIO AddOrErase (Thrustmaster
+  no-ops it).
 - **Myomers authentic coupling** — the structural un-stub is INERT (mover feed + heat-gen no-op).
   Real coupling needs the advanced-damage gate (`OwnerAdvancedDamage`/`FUN_004ad7d4` → the owning
   **BTPlayer** `mech+0x190`+0x260, NOT 0xBD3 — see the mech+0x190 item above) + `MoverAttach` routing

game/reconstructed/emitter.cpp

@@ -267,19 +267,13 @@ void
 	// what makes weapon self-heat propagate to the mech's heat sinks.
 	PoweredSubsystem::PoweredSubsystemSimulation(time_slice);
 
-	// E8 (bring-up trigger): write the weapon's fireImpulse from the player fire input
-	// (the controls mapper is bypassed).  The triggers are pulsed per-FRAME by mech4
-	// (1,0,1,0...) so CheckFireEdge sees clean rising edges for repeated auto-fire under a
-	// held/forced trigger.  HasActiveTarget (E3) limits firing to the mech with a locked
-	// target (the player) -- enemy emitters read this too but never fire (no target).
-	// WEAPON GROUPS (task #43, interim keyboard split standing in for the authentic
-	// ConfigureMappables/ChooseButton mapper channels): lasers (0xBC8=3016) and PPCs
-	// (0xBD4=3028) read SEPARATE fire channels, like two pod buttons.
-	extern int gBTWeaponTrigger;						// channel 1: lasers
-	extern int gBTPPCTrigger;							// channel 2: PPCs
-	fireImpulse = (Scalar)(((int)GetClassID() == 3028) ? gBTPPCTrigger
-														: gBTWeaponTrigger);
-
+	// AUTHENTIC TRIGGER (task #5): fireImpulse IS the published TriggerState
+	// attribute (id 0x13); the streamed per-mech controls map (type-6 resource,
+	// installed at MakeViewpointEntity) binds each grouped fire BUTTON directly
+	// onto it, and the keyboard/harness pushes press/release edges into the
+	// LBE4 buttonGroup channels (mech4).  The old gBT*Trigger bypass + the
+	// per-type keyboard split are retired -- weapons sharing a button now fire
+	// TOGETHER (the pod's authored groups: e.g. madcat Trigger = 4 weapons).
 	Logical fireEdge = CheckFireEdge();					// @004b9608
 	targetWithinRange = UpdateTargeting();				// @004b9bdc -> this+0x34c
 

game/reconstructed/mech4.cpp

@@ -112,6 +112,17 @@
 //
 
 #include <bt.hpp>
+// LBE4ControlsManager (the fire buttonGroup push, task #5) -- needs the
+// btl4app/btl4mode forward-decl order btl4mppr.cpp uses.
+#if !defined(BTL4APP_HPP)
+#	include <btl4app.hpp>
+#endif
+#if !defined(BTL4MODE_HPP)
+#	include <btl4mode.hpp>
+#endif
+#if !defined(L4CTRL_HPP)
+#	include <l4ctrl.hpp>
+#endif
 #pragma hdrstop
 
 #if !defined(MECH_HPP)
@@ -2990,12 +3001,48 @@ void
 		// (user-reported regression).  targetInArc is the explicit BT_FIRE_ARC
 		// presentation clamp (default true).  BT_AUTOFIRE holds all three.
 		{
-			const int laserWanted   = gBTDrive.fireForced || gBTLaserKey;
-			const int ppcWanted     = gBTDrive.fireForced || gBTPPCKey;
-			const int missileWanted = gBTDrive.fireForced || gBTMissileKey;
-			gBTWeaponTrigger  = (laserWanted   && targetInArc) ? (gBTWeaponTrigger  ? 0 : 1) : 0;
-			gBTPPCTrigger     = (ppcWanted     && targetInArc) ? (gBTPPCTrigger     ? 0 : 1) : 0;
-			gBTMissileTrigger = (missileWanted && targetInArc) ? (gBTMissileTrigger ? 0 : 1) : 0;
+			// AUTHENTIC FIRE INPUT (task #5): key states become PRESS/RELEASE
+			// edges pushed into the LBE4 buttonGroup channels -- the pod's own
+			// joystick path (L4CTRL Execute: Update(&v, mode) with v =
+			// +(button+1) press / -(button+1) release).  The streamed per-mech
+			// controls map binds these buttons DIRECTLY onto each grouped
+			// weapon's TriggerState@0x31C; CheckFireEdge does the rest.  This
+			// retires the gBT*Trigger globals + the 1,0 pulse hack.
+			// Desktop map: SPACE/'1' -> Trigger(0x40) [the main fire group],
+			// '2' -> ThumbLow(0x46), '3'/CTRL -> ThumbHigh(0x47) [missiles on
+			// most mechs].  BT_AUTOFIRE pulses the Trigger (edge per 2 frames).
+			// targetInArc stays the opt-in BT_FIRE_ARC presentation clamp.
+			LBE4ControlsManager *cm =
+				(LBE4ControlsManager *)application->GetControlsManager();
+			ModeMask modeMask = application->GetModeManager()->GetModeMask();
+			static int s_prevBtn[4] = {0, 0, 0, 0};
+			static int s_afPhase = 0;
+			s_afPhase ^= 1;
+			const int autofire = (gBTDrive.fireForced && targetInArc) ? s_afPhase : 0;
+			const int buttons[4] = {
+				LBE4ControlsManager::ButtonJoystickTrigger,		// 0x40
+				LBE4ControlsManager::ButtonJoystickPinky,		// 0x45
+				LBE4ControlsManager::ButtonJoystickThumbLow,	// 0x46
+				LBE4ControlsManager::ButtonJoystickThumbHigh,	// 0x47
+			};
+			int want[4];
+			want[0] = ((gBTLaserKey   && targetInArc) || autofire) ? 1 : 0;
+			want[1] = 0;										// pinky: unmapped on desktop
+			want[2] = (gBTPPCKey     && targetInArc) ? 1 : 0;
+			want[3] = (gBTMissileKey && targetInArc) ? 1 : 0;
+			if (cm != 0)
+			{
+				for (int b = 0; b < 4; ++b)
+				{
+					if (want[b] != s_prevBtn[b])
+					{
+						s_prevBtn[b] = want[b];
+						ControlsButton v = (ControlsButton)(want[b]
+							? (buttons[b] + 1) : -(buttons[b] + 1));
+						cm->buttonGroup[buttons[b]].Update(&v, modeMask);
+					}
+				}
+			}
 		}
 
 		{

game/reconstructed/mechweap.cpp

@@ -89,6 +89,10 @@ Simulation::AttributeIndexSet	MechWeapon::AttributeIndex;	// legacy empty member
 const MechWeapon::IndexEntry
 	MechWeapon::AttributePointers[]=
 {
+	// The authentic entry (binary table @0x511890): the streamed controls maps
+	// bind the pod fire buttons directly onto this Scalar -- fireImpulse IS the
+	// binary's "TriggerState" (the edge-detected fire channel destination).
+	ATTRIBUTE_ENTRY(MechWeapon, TriggerState,  fireImpulse),	// @0x31C  id 0x13
 	ATTRIBUTE_ENTRY(MechWeapon, OutputVoltage, rechargeLevel),	// @0x320 (charge/ready level)
 	ATTRIBUTE_ENTRY(MechWeapon, PercentDone,   rechargeLevel)	// @0x320 (recharge dial fraction)
 };

game/reconstructed/mechweap.hpp

@@ -122,8 +122,21 @@ class CockpitHud;
 	//
 	public:
 		enum {
-			OutputVoltageAttributeID = PoweredSubsystem::NextAttributeID,
-			PercentDoneAttributeID,
+			// TriggerState is the BINARY's only MechWeapon attribute
+			// ({0x13, "TriggerState", +0x31d} @0x511890 -- fireImpulse@0x31C).
+			// The streamed per-mech controls maps (type-6 resources) bind the
+			// fire buttons DIRECTLY onto it by this NUMERIC id, so it is
+			// PINNED to the binary value: the binary's subsystem chain reaches
+			// 0x12 before MechWeapon (ConfigureActivePress@MechSubsystem=2,
+			// heat family 3..0xC, powered/aux-screen family 0xD..0x11 -- full
+			// dump in the task #5 attr-table scan), while our reconstruction
+			// publishes fewer base attrs (chain value 0xD).  The id gap wastes
+			// a few dense-index slots (Build sizes by max id) -- harmless.
+			// OutputVoltage/PercentDone are port gauge additions
+			// (name-resolved) renumbered after it.
+			TriggerStateAttributeID = 0x13,
+			OutputVoltageAttributeID,		// 0x14
+			PercentDoneAttributeID,			// 0x15
 			NextAttributeID
 		};
 	private:

game/reconstructed/myomers.cpp

@@ -464,9 +464,16 @@ void Myomers::ResetToInitialState(Logical powered)
 
 
 //***************************************************************************
-// Myomers::ConnectToMover                                        @004b9550
+// Myomers::ConnectToMover                                        (mislabeled)
 //***************************************************************************
 //
+// ⚠ MISATTRIBUTION (task #5 correction): @004b9550/@004b95b8 are NOT Myomers
+// functions -- the weapon message-table @0x511860 proves they are
+// MechWeapon::ConfigureMappables (id 9) / ChooseButton (id 10), the weapon->
+// button grouping handlers (the +0x31C coincidence: Myomers speedEffect vs
+// MechWeapon TriggerState).  The bodies below are retained as the port's
+// Myomers stand-ins but carry no binary address.
+//
 // Attaches the live SpeedEffect output (@0x31C) into the Mech's JointedMover
 // roster (the mover at **(Mech[0xD0]+0x128)).  Driven by a connect message
 // whose payload index is at message+0xC:

game/reconstructed/projweap.cpp

@@ -534,21 +534,15 @@ void
 	DrawFiringCharge(time_slice);						// @004bbc78 -- bleed recoil (+0x3E8)
 	UpdateEject(time_slice);							// @004bbb50 -- idle unless ejectState==0
 
-	// 2. Rising-edge trigger from the owning Mech's discharge signal.
-	//    Bring-up: the controls mapper is bypassed, so drive fireImpulse from the
-	//    per-frame trigger pulse -- else CheckFireEdge never sees an edge and a
-	//    projectile weapon never fires.  SPLIT CONTROLS (interim, toward the real
-	//    controls-mapper weapon groups): projectile weapons (the missile
-	//    launchers, cannon) fire on the MISSILE channel (CTRL), not the
-	//    energy-weapon channel (SPACE) -- one key no longer fires everything.
-	extern int gBTMissileTrigger;
-	fireImpulse = (Scalar)gBTMissileTrigger;			// this+0x31C
+	// 2. AUTHENTIC TRIGGER (task #5): fireImpulse = the TriggerState attribute
+	//    the streamed controls map binds to the pod fire buttons (see emitter.cpp
+	//    note).  The gBTMissileTrigger bypass is retired.
 	Logical trigger = CheckFireEdge();					// MechWeapon @004b9608
 
 	static int s_pwtick = 0;
 	if (getenv("BT_PROJ_LOG") && (((++s_pwtick) % 240) == 0 || trigger))
 		DEBUG_STREAM << "[projweap] tick " << GetName() << " trig=" << (int)trigger
-			<< " gTrig=" << gBTMissileTrigger << " ready=" << (int)ReadyToFire()
+			<< " trigState=" << (float)fireImpulse << " ready=" << (int)ReadyToFire()
 			<< " state=" << weaponAlarm.GetState() << " recoil=" << recoil << " x\n" << std::flush;
 
 	// 3. Firing state machine (weaponAlarm @0x350).  Modelled on the RP analog

scratchpad/ab.py

@@ -0,0 +1,9 @@
+from PIL import Image
+import numpy as np
+a=np.array(Image.open('scratchpad/cop_fwd_s.png').convert('RGB').resize((360,270)))
+b=np.array(Image.open('scratchpad/cop_flip_s.png').convert('RGB').resize((360,270)))
+gap=np.full((270,6,3),255,np.uint8)
+Image.fromarray(np.concatenate([a,gap,b],axis=1)).save('scratchpad/cop_ab.png')
+def stat(x): return "mean=%s greenfrac=%.2f"%(x.reshape(-1,3).mean(0).round(0), ((x[:,:,1]>100)&(x[:,:,0]<80)).mean())
+print("forward:",stat(a)); print("flip:   ",stat(b))
+print("saved cop_ab.png [forward | flip]")

scratchpad/bgf_parse.py

@@ -0,0 +1,102 @@
+#!/usr/bin/env python3
+"""Robust BGF (DIV-BIZ2) parser for the cockpit-shell reconstruction harness.
+Handles the vertex-format chunks the engine loader (bgfload.cpp) does:
+  0x80 XYZ(12)  0x81 XYZ_N(24)  0x82 XYZ_RGBA(28)
+  0x88 XYZ_UV(20) 0x89 XYZ_N_UV(32) 0x8A XYZ_RGBA_UV(36)
+Faces: 0x47 index list (u32 tri indices), 0x4d poly list (ppf-prefixed u32).
+Tree: 0x40 container / 0x41 object / 0x42 patch / 0x46 mesh; 0x2037 SV_SPECIAL
+(carries "PUNCH"); 0x2030 material name.  Face indices are patch-local (base=patch
+vert start).  Returns per-patch geometry so we see frame vs glass vs punch."""
+import struct
+
+VSTRIDE = {0x80:12, 0x81:24, 0x82:28, 0x88:20, 0x89:32, 0x8A:36}
+VHASN   = {0x81, 0x89}
+VHASUV  = {0x88, 0x89, 0x8A}
+CONTAINERS = {0x40,0x41,0x42,0x46,0x48,0x70,0x10,0x20,0x30,0x3}
+
+def parse(path):
+    d = open(path,"rb").read()
+    patches = []   # each: dict(material, punch, verts[list (x,y,z,has_n,nx,ny,nz,u,v)], faces[list (a,b,c)])
+    cur = {"material":"", "punch":False}
+    def read_chunk(p, end):
+        if p+2 > end: return None
+        tw = struct.unpack_from("<H", d, p)[0]
+        cid = tw & 0x2fff
+        lw = 4 if (tw & 0x8000) else (2 if (tw & 0x4000) else 1)
+        if p+2+lw > end: return None
+        if lw==1: ln = d[p+2]
+        elif lw==2: ln = struct.unpack_from("<H", d, p+2)[0]
+        else: ln = struct.unpack_from("<I", d, p+2)[0]
+        body = p+2+lw
+        return cid, body, ln, body+ln
+    def walk(p, end, patch):
+        while p < end:
+            r = read_chunk(p, end)
+            if not r: break
+            cid, body, ln, nxt = r
+            if cid == 0x42:            # new patch
+                patch = {"material":"", "punch":False, "verts":[], "faces":[]}
+                patches.append(patch)
+                walk(body, nxt, patch)
+            elif cid == 0x2030:        # material name (string)
+                if patch is not None:
+                    patch["material"] = d[body:body+ln].split(b'\0')[0].decode('latin1','ignore')
+            elif cid == 0x2037:        # SV_SPECIAL -> PUNCH?
+                if patch is not None and b"PUNCH" in d[body:body+ln]:
+                    patch["punch"] = True
+            elif cid in VSTRIDE:       # vertex chunk -> this submesh's face indices are
+                st = VSTRIDE[cid]; hasn = cid in VHASN; hasuv = cid in VHASUV
+                patch["_base"] = len(patch["verts"])   # local to THIS chunk (base offset)
+                n = ln // st
+                for i in range(n):
+                    o = body + i*st
+                    x,y,z = struct.unpack_from("<fff", d, o)
+                    nx=ny=nz=0.0; u=v=0.0; off=12
+                    if hasn:
+                        nx,ny,nz = struct.unpack_from("<fff", d, o+off); off+=12
+                    if hasuv:
+                        u,v = struct.unpack_from("<ff", d, o+off)
+                    patch["verts"].append((x,y,z,hasn,nx,ny,nz,u,v))
+            elif cid == 0x47:          # tri index list (indices local to last vertex chunk)
+                b = patch.get("_base",0); n = ln//4
+                idx = [struct.unpack_from("<I", d, body+i*4)[0] for i in range(n)]
+                for f in range(0,(n//3)*3,3):
+                    patch["faces"].append((b+idx[f],b+idx[f+1],b+idx[f+2]))
+            elif cid == 0x4d:          # poly list (ppf-prefixed)
+                if ln>=1:
+                    b = patch.get("_base",0); ppf = d[body]; n=(ln-1)//4
+                    idx=[struct.unpack_from("<I",d,body+1+i*4)[0] for i in range(n)]
+                    for f in range(0,(n//ppf)*ppf,ppf):
+                        poly=[idx[f+j] for j in range(ppf)]
+                        for k in range(1,ppf-1):
+                            patch["faces"].append((b+poly[0],b+poly[k],b+poly[k+1]))
+            elif cid in CONTAINERS:
+                walk(body, nxt, patch)
+            p = nxt
+    walk(8, len(d), None)
+    return [pt for pt in patches if pt["verts"] and pt["faces"]]
+
+if __name__ == "__main__":
+    import sys, numpy as np
+    from collections import Counter
+    path = sys.argv[1] if len(sys.argv)>1 else "content/VIDEO/GEO/MAX_COP.BGF"
+    P = parse(path)
+    print(f"{path}: {len(P)} patches")
+    allV=[]; ec=Counter(); tot_faces=0; punch_faces=0
+    for i,pt in enumerate(P):
+        V=np.array([(v[0],v[1],v[2]) for v in pt["verts"]])
+        hasuv = any(v[7]!=0 or v[8]!=0 for v in pt["verts"])
+        hasn  = any(v[3] for v in pt["verts"])
+        F=pt["faces"]
+        lo=V.min(0); hi=V.max(0); cen=V.mean(0)
+        for a,b,c in F:
+            if max(a,b,c)>=len(V): continue
+            for e in ((a,b),(b,c),(c,a)): ec[tuple(sorted(e))]+=1
+        tot_faces+=len(F)
+        if pt["punch"]: punch_faces+=len(F)
+        print(f"  patch{i}: mtl='{pt['material'][:30]}' punch={pt['punch']} "
+              f"verts={len(V)} faces={len(F)} uv={hasuv} n={hasn} "
+              f"cen=({cen[0]:.2f},{cen[1]:.2f},{cen[2]:.2f}) "
+              f"bbox=[{lo[0]:.2f},{lo[1]:.2f},{lo[2]:.2f}]..[{hi[0]:.2f},{hi[1]:.2f},{hi[2]:.2f}]")
+    bound=sum(1 for k,vv in ec.items() if vv==1)
+    print(f"TOTAL faces={tot_faces} punch_faces={punch_faces} boundary_edges={bound}/{len(ec)}")

scratchpad/bgfparse.py

@@ -0,0 +1,51 @@
+import struct,sys
+
+def rdU16(b,p): return struct.unpack_from('<H',b,p)[0]
+def rdU32(b,p): return struct.unpack_from('<I',b,p)[0]
+def rdF32(b,p): return struct.unpack_from('<f',b,p)[0]
+
+TAGNAME={0x0003:'HEADER',0x0005:'BIZ_DONE',0x0040:'OBJECT',0x0041:'LOD',0x0042:'PATCH',
+0x0046:'PMESH',0x0047:'CONN_LIST',0x0048:'SPHERE_LIST',0x004d:'PCONN_LIST',0x0070:'BOUND',
+0x0080:'VTX_XYZ',0x0081:'VTX_XYZ_N',0x0082:'VTX_XYZ_RGBA',0x0088:'VTX_XYZ_UV',
+0x0089:'VTX_XYZ_N_UV',0x008A:'VTX_XYZ_RGBA_UV',0x2030:'SV_F_MATERIAL',0x2037:'SV_SPECIAL',
+0x0010:'TEXTURE',0x0011:'TEXTURE_MAP',0x0018:'BITSLICE',0x0020:'MATERIAL',
+0x0021:'MAT_TEXTURE',0x0023:'AMBIENT',0x0024:'DIFFUSE',0x0026:'EMISSIVE',
+0x0028:'RAMP_REF',0x0030:'RAMP',0x0031:'RAMP_DATA',0x2008:'NAME',
+0x0043:'FACE',0x0044:'FACE?',0x0045:'FACE?'}
+CONTAINERS={0x0003,0x0070,0x0040,0x0041,0x0042,0x0046,0x0048,0x0010,0x0020,0x0030}
+
+def parse(b,p,end,depth,out):
+    while p+3<=end:
+        tw=rdU16(b,p); p+=2
+        idv=tw & 0x2fff
+        lw=4 if (tw&0x8000) else (2 if (tw&0x4000) else 1)
+        if p+lw>end: break
+        ln = b[p] if lw==1 else (rdU16(b,p) if lw==2 else rdU32(b,p))
+        p+=lw
+        if p+ln>end: break
+        out.append((depth,idv,p,ln))
+        if idv in CONTAINERS:
+            parse(b,p,p+ln,depth+1,out)
+        p+=ln
+        if idv==0x0005: break
+    return
+
+fn=sys.argv[1]
+b=open(fn,'rb').read()
+assert b[:8]==b'DIV-BIZ2', b[:8]
+out=[]
+parse(b,8,len(b),0,out)
+for depth,idv,p,ln in out:
+    nm=TAGNAME.get(idv,'?%04x'%idv)
+    extra=''
+    if idv==0x2008 or idv==0x0011 or idv==0x0028:
+        s=b[p:p+ln].split(b'\0')[0].decode('latin1',errors='replace')
+        extra='  "%s"'%s
+    if idv==0x2037: # SV_SPECIAL
+        s=b[p:p+ln].split(b'\0')[0].decode('latin1',errors='replace')
+        extra='  SPECIAL="%s"'%s
+    if idv==0x2030: # SV_F_MATERIAL
+        s=b[p:p+ln].split(b'\0')[0].decode('latin1',errors='replace')
+        extra='  MAT="%s" (len %d)'%(s,ln)
+    if idv==0x0018 and ln>=1: extra='  slice=%d'%b[p]
+    print('  '*depth + '%-14s off=0x%04x len=%d%s'%(nm,p,ln,extra))