# Mission scoring and the S/A/B/C/D rank thresholds

**✅ Settled 2026-08-27** (static; regenerator
`tools/re-capture/mission_scoring.py`, artefact
[`data/mission-scoring.txt`](../data/mission-scoring.txt)).

Found by following `sub_8230D1F8` — the loader that the `AA_`/`AV_` investigation
turned up as a *contaminant*, because it stores at the same object offsets the
unit definition uses. Reading its field names instead of its offsets identified
it as the **stage-settings loader**, and the scoring block is the part of it the
corpus did not have.

**Docs checked:** `isl-condition-builtins.md` owns `AUTO_SETTINGS` — the 28
`stageNN_settings.tbl` / `tutorialNN` / `challengeNN` **filenames**;
`unit-datasheet-static.md` and `unit-struct-runtime.md` own the *per-unit*
`ScorePoint` / `DamageScore` / `MassScore` fields. **What none of them says is how
a mission score is assembled or what earns a rank** — `RankScore`, `TimeBonus`,
`KillBonus`, `FFPenalty`, `Difficulty_*` appear nowhere in `docs/re/`.

## The tables

**24 IDXD objects per language pack × 6 packs = 144.** Each holds exactly three
records — `Score_Easy`, `Score_Normal`, `Score_Hard` — so **72 scoring records
per pack**, and they share **one** 22-field schema with no variants.

| group | fields |
|---|---|
| rank thresholds | `RankScore_S` `_A` `_B` `_C` `_D` |
| score multipliers | `CraftScore_Adjustment`, `VesselScore_Adjustment`, `OtherScore_Adjustment` |
| objective bonus | `MainMissionCount`, `MainMissionBonus` |
| time bonus | `TimeBonus_Maximun` (sic), `TimeBonus_Basis_Minimum`, `TimeBonus_Basis_Maximum` |
| kill / escort bonus | `KillBonus_Maximum`, `FriendlyVesselDamageBonus`, `GettingScoreBasis_Minimum`, `GettingScoreBasis_Maximum` |
| penalties | `LostWingmanPenalty`, `FFPenalty_Craft_Basis`, `FFPenalty_Craft_Maximum`, `FFPenalty_Vessel_Basis`, `FFPenalty_Zessel_Maximum` (sic — "Vessel") |

Two of the game's own misspellings are load-bearing as join keys:
**`TimeBonus_Maximun`** and **`FFPenalty_Zessel_Maximum`**.

## ✅ Difficulty changes the earning rate, not the bar

Comparing the three difficulty records inside each object, **10 of the 22 fields
move and 12 never do** — and the ones that never move include **all five
`RankScore_*` thresholds**:

```
differ between Easy/Normal/Hard   CraftScore_Adjustment 21   VesselScore_Adjustment 21
(count = objects out of 24)       OtherScore_Adjustment 21   LostWingmanPenalty     21
                                  FFPenalty_Craft_Maximum 21 FFPenalty_Zessel_Maximum 21
                                  KillBonus_Maximum      18  MainMissionBonus       18
                                  TimeBonus_Maximun      18  FriendlyVesselDamageBonus 13
never differ                      RankScore_S/A/B/C/D, MainMissionCount,
                                  GettingScoreBasis_*, TimeBonus_Basis_*,
                                  FFPenalty_*_Basis
```

So a rank bar is **per stage**, identical on every difficulty; what difficulty
changes is how fast you earn against it (`×0.5` / `×1.0` / `×2.0` on the three
`*Score_Adjustment` multipliers) and how hard the penalties bite. That is a
design statement a port has to reproduce exactly, and it is measured, not read
off the names.

## Per-stage variation

**23 of the 24 objects differ from the commonest `Score_Normal` record**, almost
always in the `RankScore_*` thresholds and the objective count/bonus — as
expected for per-mission tuning. Nine of the 72 records (three objects × three
difficulties) zero the multipliers, the penalties and `TimeBonus_Maximun`
outright: missions that are not scored. Full per-object diffs are in the
artefact.

## ✅ Which object is which stage — settled

All 24 are named `stage\StageParameter_S<NN>.tbl`, plus `_Tutorial` (shared by
all six tutorials) and `_Test`. See
[`stage-settings-table.md`](stage-settings-table.md); that also explains 24
against the 29 stage records, and confirms the `IsBoss16Enable` object is S16.

⚠️ The names are **not** `AUTO_SETTINGS`'s `stageNN_settings.tbl`; none of those
28 hashes to any of these objects.