re: the destructible-subsystem model -- a unit's sub-records

The corpus has named these since unit-struct-runtime.md but never
opened them.  Per unit table: Turret_NNN 835 records (max 63 on one
unit), ShieldGenerator_NNN 46, Thruster_NNN 38, Hatch_NNN 26,
Bridge_NNN 25, plus one each of Shield/Mass/SE/Explosion/
StructureCount and NS_Body on 68 of 114.

Turret/ShieldGenerator/Thruster/Hatch/Bridge are ONE record shape: a
shared 19-field destructible-part base (ID, Name, ParentStructureID,
Frame = a mesh NODE name, NomalModel, CollisionModel, Radius, HP, the
four Is* flags, SpreadDamage, damaged/destroy motion + time, and the
three Effect_*), with per-kind extras.  Turrets add WeaponID,
AngularVelocity, YawLimit, PitchLimit_Elevation/_Depression, CoverArea,
IsAuto, HasBarrel and up to 80 CannonModel_NNN/CannonFrame_NNN.  Shield
generators, thrusters and bridges add PowerRatio.  Hatches add
SquadronID, LoadedCount, MaxAvailableCount, TakeoffInterval -- a
carrier's launch bay.

Control 1: StructureCount.<Kind>Count == #<Kind>_NNN records, over 684
comparisons -- 612 equal, 55 "0 declared, one blank placeholder"
(55/55 blank in Name AND NomalModel AND Frame), 11 differ, 6 kind
absent.  All 11 exceptions are Turret and all are declared < records.

Control 2: 835/835 Turret_NNN.WeaponID resolve to an ID in the
131-record Weapon datasheet, zero unresolved; 26 weapons are never
mounted on a turret.

Refuted in the same pass: "the DeltaSaber's 59 non-NULL hardpoints are
the 59-name WEAPONS arsenal roster".  The counts match exactly and the
sets overlap in 0 values -- two namespaces, one coincidence.

New structure doc, artefact and regenerator; other artefacts unchanged.

docs/re/structures/unit-substructure-records.md

@@ -0,0 +1,131 @@
+# ✅ The destructible-subsystem model — a unit's sub-records
+
+The corpus has named the sub-records of a unit `.tbl` since
+[unit-struct-runtime](unit-struct-runtime.md) ("`Generic`, `Maneuver`,
+`Shield`, `Explosion`, `Mass`, `Effect`, `SE`, `Turret_00N` … all flattened
+into that single object") but has never **opened** them. This does.
+
+One unit = one IDXD pak entry. 114 of them
+([the `Generic` partition](unit-datasheet-static.md)). Artefact
+`../data/unit-substructures.txt`, regenerator
+`tools/re-capture/unit_substructures.py`.
+
+| family | records | max/unit | non-indexed fields |
+|---|---:|---:|---:|
+| `Turret_NNN` | **835** | 63 | 38 |
+| `Generic` / `Maneuver` / `Effect` / `Shield` / `Mass` / `SE` / `Explosion` / `StructureCount` | 114 each | 1 | — |
+| `NS_Body` | 68 | 1 | 12 |
+| `ShieldGenerator_NNN` | 46 | 4 | 21 |
+| `Thruster_NNN` | 38 | 4 | 21 |
+| `Hatch_NNN` | 26 | 4 | 23 |
+| `Bridge_NNN` | 25 | 2 | 20 |
+
+Seven singletons named with a literal `???` (`Turret_???`, `Versatile_???`, …)
+are the schema's own template rows.
+
+## The shared destructible-part base
+
+`Turret`, `ShieldGenerator`, `Thruster`, `Hatch` and `Bridge` are the **same
+record shape** with per-kind extras. Every one of the 970 part records carries:
+
+```
+ID  Name  ParentStructureID  Frame  NomalModel  CollisionModel  Radius
+HP  IsDestructible  IsShielded  IsInvolved  IsRadarVisible  SpreadDamage
+DamagedMotionName  DestroyMotionName  DestroyMotionTime
+Effect_Explosion  Effect_Flare  Effect_Paralyze
+```
+
+(`NomalModel` is the game's own spelling.) `Frame` is a **mesh node name** —
+`GN_mnt` on the player craft — so a part is bolted to a named bone of the
+`Generic.Model` mesh the corpus already decodes.
+
+Per-kind, on top of that base:
+
+| kind | extra fields |
+|---|---|
+| `Turret` | `WeaponID`, `AngularVelocity`, `YawLimit`, `PitchLimit_Elevation`, `PitchLimit_Depression`, `CoverArea`, `IsAuto`, `HasBarrel`, `CommonCannonModel`/`Frame`, `CannonModel_NNN`/`CannonFrame_NNN` (up to 80), `SequencingCount`, `SequencingInterval`, and on a few: `CurveAngle`, `FCSAngle`, `FollowView`, `ShellModel`, `CoverModel` |
+| `ShieldGenerator` / `Thruster` / `Bridge` | `PowerRatio` — losing the part degrades the parent |
+| `Thruster` | `NozzleCount` |
+| `Hatch` | `SquadronID`, `LoadedCount`, `MaxAvailableCount`, `TakeoffInterval` — **a carrier's launch bay** |
+
+🔑 That is a complete component model: named bone, own mesh and collision mesh,
+own HP and destruction motion + effects, and a `PowerRatio` saying what the
+parent loses when it dies.
+
+## The one-record blocks
+
+| record | fields |
+|---|---|
+| `Shield` | `MaxValue`, `ChargeSpeed`, `ChargeDelay`, `ChargeDelay_Break` |
+| `Mass` | `DryMass`, `GrossMass` |
+| `SE` | `ExplosionSE`, `Thruster`, `SideThruster`, `JumpIn`, `JumpOut`, `ShipEnvironmentSE`, `LowerHPSE`, `LowerHPThresholdRatio` |
+| `Explosion` | `Delay`, `DelayAdjustment`, `ExplosionFxModel`, `ExplosionMotionName`, `LowerHPFxModel`, `DestroyMotionName`, `DestroyMotionTime` |
+| `StructureCount` | `TurretCount`, `BridgeCount`, `HatchCount`, `ShieldGeneratorCount`, `ThrusterCount`, `VersatileCount` |
+| `NS_Body` | `Model`, `NodeCount`, `Interval`, `StartingVelocity`, `Deceleration`, `Volume`, `Color_R/G/B`, `AttenuationVolume`, `AttenuationAlpha`, `DeleteFadeSpeed` — an engine-trail ribbon, on 68 of 114 |
+
+Every field the runtime doc reached for `Shield` (`MaxValue +0x238`,
+`ChargeSpeed +0x244`) and `Mass` (`DryMass +0x274`, `GrossMass +0x278`) is
+here, at the same names.
+
+## 🧪 Control 1 — `StructureCount` counts the part records
+
+`declared == #<Kind>_NNN records`, over 114 units × 6 kinds = 684:
+
+| | |
+|---|---:|
+| equal | **612** |
+| declared 0, one blank placeholder record | 55 |
+| differs | **11** |
+| kind absent from `StructureCount` | 6 |
+
+The 55 are a real sub-rule, not slack: a kind with a count of **0 still emits
+exactly one record**, and all 55 have empty `Name`, `NomalModel` *and* `Frame`.
+So the file always carries at least one slot per kind.
+
+Every one of the 11 exceptions is a **`Turret`**, and every one has
+`declared < records` — never the other way round. Nine are the player's
+DeltaSaber family:
+
+```
+declared=4  records=63   x7   f001_T, f001_T_EX5, f001_T_EX5_el, f001_T_Player,
+                              f002_W, f002_W_Player, f004_A_Player
+declared=4  records=5    x2   f001_T_Player_Ttrl1 / _Ttrl2
+declared=1  records=2    x1   UN_e001_ADAN_Elan_EX4
+declared=8  records=9    x1   UN_e107_ADAN_AAFrigate_EX4
+```
+
+🟡 The reading — **not adopted**: on the player craft the `Turret_NNN` list is
+a *hardpoint catalogue* and `TurretCount 4` is how many mount at once. It fits
+(63 slots, all `Frame=GN_mnt`, all `IsAuto=No`, 10 distinct `WeaponID`s across
+them, and the tutorial variants carry a cut-down 5) but nothing here shows the
+selection. The two `+1` warship/craft cases are unexplained.
+
+## 🧪 Control 2 — turret weapons resolve into the weapon datasheet
+
+**835 / 835 `Turret_NNN.WeaponID` values are an `ID` in the 131-record
+`Weapon` table. Zero unresolved.** 105 distinct values are used; **26 of the
+131 weapons are never mounted on a turret** — the player-only arsenal.
+
+That is a hard cross-table link: [the weapon
+datasheet](weapon-datasheet-static.md) is what arms every gun on every ship.
+
+## ❌ Refuted in the same pass — "the 59 hardpoints are the 59-name arsenal roster"
+
+The DeltaSaber's 63 turret slots hold **59 non-`Weapon_NULL`** entries, and the
+`WEAPONS` roster in `GP_HANGAR_ARSENAL.pak` has exactly **59** names. Tempting,
+and wrong: the two sets **overlap in 0 values**, and the 59 slots carry only
+**10 distinct** `WeaponID`s. The roster is display names
+(`Machiene_Cannon_MG1` — the game's spelling); the hardpoints reference
+`Weapon.ID` (`Weapon_TCAF_DeltaSaber_Gun`). Two namespaces, one coincidence of
+count.
+
+## 🟡 Not settled
+
+* What links a roster entry to a `Weapon.ID` — the 59-of-131 question is still
+  open, and this pass shows the answer is **not** the hardpoint list.
+* `Versatile_NNN` has 0 populated records in this pak; only the `???` template
+  row exists, so its schema is known and its instances are not.
+* `CoverArea` reads as a hex word (`0x00000000` / `0x00000001`) — a bit mask,
+  bits unknown.
+* The 6 `no field` comparisons are one unit whose `StructureCount` omits every
+  count.