# `stage\UnitGroup_S.tbl` — the per-stage squadron roster Status: ✅ container format and field semantics, validated across all 28 stage tables present on the disc; 🟡 one member field; ❔ the record key and the arrival-interval *values*. Reached from the per-stage definition record's `EnumerateSquadron` field — see [stage-definition-table.md](stage-definition-table.md). Tool: `tools/re-capture/unitgroup.py` (pure static; runs no emulator). ``` python3 tools/re-capture/unitgroup.py S02 # full roster python3 tools/re-capture/unitgroup.py --all --check # self-check every stage ``` A committed dump of Stage 02 is at [`../data/unitgroup-s02.txt`](../data/unitgroup-s02.txt). ## ✅ Container ``` 0x00 "IDXD" 0x04 u32 nrec 0x08 nrec x 16 record: (key, squadron_off, field_lo, field_hi) u32 npool npool x 12 property entry: (tag, name_off | 0xffffffff, value_off) u32 strsize -- and STR + strsize == filesize, exactly strsize string pool; [0] = "Enumerate_Squadrons", [0x14] = "" ``` **Every offset in the file is relative to `STR`**, the string-pool base. A record's fields are pool entries `[field_lo, field_hi)`. An entry with `name_off == 0xffffffff` is *positional*; otherwise the entry carries its own field name inline, so the table is self-describing and the tag hash never has to be inverted. Exactly one record per file is not a squadron: it is the **`Enumerate_Squadrons` roster**, whose entries map `key -> squadron id` for every other record. It is usually the last record but not always — in S05, S06, S07, S08, S09, S11, S13, S28 and S29 it sits elsewhere, so find it by its missing `Count`, not by position. ## ✅ A squadron record Five named fields, always present and always these five: | field | values | |---|---| | `Count` | 1 (×1082), 2 (×50), 3 (×8), 4 (×20) | | `SideID` | `ADAN` (745), `TCAF` (294), `Neutral` (121) | | `AIID` | 31 distinct, e.g. `AI_ADAN_CraftSquadron_Veteran`, `AI_TCAF_BirdFlight`, `AI_ADAN_Fleet`, `AI_Structure`, `AI_TraceRoute` | | `FormationID` | e.g. `Formation_4_Bird`, `Formation_ADAN_Turret07_30`, `Formation_1_only` | | `DisableInterval` | `No` (1129), **`Yes` (31)** | …preceded by `Count` **member tuples** of four positional entries: ``` (unit model, message set, n, identity) ``` * unit model — 122 distinct, and they are our XBG7 mesh names: `UN_f001_TCAF_DeltaSaber_T_Player`, `UN_e010_ADAN_Attacker_S`, `UN_e007_ADAN_Turret`, `UN_bf001_TCAF_SchlosBase`. * message set — the squadron's radio chatter, e.g. `MessageSet_Ellen`, `MessageSet_ADAN_plA`. * `n` — ✅ **the number of units this tuple instantiates**, filling slots of the squadron's formation. Integer 1…30, dominated by 1 (735) and 9 (197). See *"What `n` counts"* below — the old note that it is "not the `_NN` suffix of `FormationID`" was right but drew the wrong conclusion. * identity — 63 distinct: named pilots (`ELLEN`, `SANDRA`, `RAYMOND`, `YOJI`), ship nameplates (`NP_Charon`, `NP_Amalthea`, `NP_Olympus`), carrier tags (`Carrier_ADAN01`), cargo tags (`CARGO_1`), or empty. Worked example — Stage 02, squadron `TCN004`, the player's own flight: ``` TCN004 TCAF Count=2 DisableInterval=No Formation_2_Rhino1 AI_TCAF_RhinoFlight unit=UN_f001_TCAF_DeltaSaber_T_Player msg=MessageSet_Katana n=1 id=Character_Player_Test unit=UN_f001_TCAF_DeltaSaber_T msg=MessageSet_Ellen n=1 id=ELLEN ``` ## ✅ Two independent self-checks, both corpus-wide 1. **`len(fields) == Count * 4 + 5`** — holds for **1160 of 1160** squadrons across all 28 stage tables. This is what pins the member-tuple width at 4 and the named-field count at 5; it was not assumed. 2. **Roster agreement** — the `Enumerate_Squadrons` record's `key -> id` mapping agrees with the name each record resolves independently through its own `squadron_off`, for **1160 of 1160**. S17 has no `stage\UnitGroup_S17.tbl` in `GP_MAIN_GAME_E.pak`, matching the missing S17 stage record. ## ❌ Refuted along the way * **The record key is not the squadron id's name hash.** `name_hash("TCN001") = 0xd639f1a4`, but the keys run `0x659aff47, 0x659b0046, 0x669b0047, …` — 0 of 112 match. What the key encodes is still ❔. Its byte structure (`b0` ramping, `b2` taking small signed values) looks like a packed tuple, untested. * **Squadron ids do not use a separate string base.** An earlier reading here put them at `STR + 0x15` and scored "109 of 111", which looked like a near-fit but was an artefact of the uniform 7-byte id stride — it silently shifted every name by three entries (record 0 read as `ADN104` instead of `ADN101`, and 17 `TC*`-named squadrons came out with `SideID = ADAN`). The roster record refuted it outright, and with the correct base — plain `STR` — agreement is 111/111. The lesson is that a 98 %-looking score on a self-consistent stride is not evidence; the roster was an independent oracle and should have been consulted first. * **The 20-byte "section header"** described in an earlier draft of [stage-definition-table.md](stage-definition-table.md) does not exist. What looked like `(tag, 0, 0, count, size)` was the file's last 16-byte record followed by the `npool` word. The corrected layout above is uniform across all 28 files, which the earlier reading was not — it failed on 9 of them. ## What is still open * The meaning of the 4-byte record key. * The member tuple's third field `n`. * **The interval values.** `DisableInterval` is a per-squadron *flag* and 31 squadrons set it, but the interval durations, spawn triggers and arrival positions are not in this file. The next places to look are `Formation_*.tbl` (the formation geometry and possibly its timing) and `EnumSquadron_Test.tbl`, both named by the stage record. ## ✅ What `n` counts — bounded by the formation, 1159 of 1160 `n` is the **number of units the member tuple instantiates**. The evidence is a hard, falsifiable inequality against a table `UnitGroup` never mentions. `FormationSet_S.tbl` is the same IDXD container, and a formation record is a **slot list**: one named field `FrameCount` plus 8 positional fields per slot — `FrameCount = 4 → 33` fields, `14 → 113`, `30 → 241`, `32 → 257`, i.e. `1 + 8·FrameCount`, exactly. Resolving each squadron's `FormationID` to its formation (below) and comparing: ``` sum(n) <= FrameCount: HOLDS 1159 VIOLATED 1 unresolved 0 of the holders, sum(n) == FrameCount exactly: 539 ``` Across all 28 stages, **every** `FormationID` resolves and **every** squadron but one fits its formation, with 46 % filling it exactly. A field unrelated to formation size would not do that. **The one violation is a debug leftover**, recorded rather than swept up: S20 (a tutorial stage), `Formation_1_only` (`FrameCount = 1`) with `n = 2` — `AIID = AI_Test`, `msg = MessageSet_test`, no identity, unit `UN_e015_ADAN_Puppy_2`. It is still a literal violation of the invariant. ### ✅ The formation name's trailing number IS `FrameCount` `Formation_ADAN_Turret07_30` → `FrameCount = 30`; `Formation_TCAF_ArrowHead02_32` → 32; `Formation_4_Bird` → 4 (leading, this family has no suffix). So the old observation that `n = 9` does not match the `_30` in `Formation_ADAN_Turret07_30` is correct and **not** evidence against `n` being a count: 9 units occupy 9 of that formation's 30 slots. ### ❌ WITHDRAWN — "`FormationID` does not hash into the table" **It does.** The refutation below used the wrong hash function. A record key is [`tag_hash`](idxd-tag-hash.md) of the record's own name — *not* the pak-TOC `name_hash`, which lowercases and uses a different modulus. Checked directly: ``` tag_hash("Formation_4_Bird") = 0x22a5eeed <- exactly the record key name_hash("Formation_4_Bird") = 0x6286edad <- the wrong hash, hence "0 of 16" ``` `Formation_4_Bird` **is** a record name in `FormationSet_S02.tbl`, and every record in that table keys by `tag_hash` of its name. Across all 28 `UnitGroup_S.tbl` the same holds for field keys: **6960 / 6960** are `tag_hash(field name)` and **0** are `name_hash`. So `FormationID` resolves by a direct hash lookup and the roster indirection is **not required** for it. This is the exact trap [`idxd-container.md`](idxd-container.md) warns about, and it cost this file a spurious ❌. 🟡 The *squadron* half of the original claim still stands: a squadron record's key is not `tag_hash` of the squadron id either (`tag_hash("TCN001")` = `0x760cdeaa`, against keys running `0x659aff47…`), because the record's **name** is not the squadron id. The roster maps id → record, and that indirection is real. ### The original text, kept `FormationID` does **not** hash into the table: `name_hash("Formation_4_Bird")` = `0x6286edad`, and the record key is `0x22a5eeed` — 0 of 16 resolve that way. `FormationSet_S02.tbl` has **17 records for 16 formations**, and the extra one is a **name roster**, exactly like `Enumerate_Squadrons` here: it carries no `FrameCount` and its fields are `(tag, name, "")` triples whose **tags are the record keys**. Find it by its missing `FrameCount`, map name → key, done. That is the same convention twice in two different tables, which is worth remembering for the next one: **a table's record keys are resolved by a roster record inside the table, not by hashing the name.** ### 🟡 What this does not settle * It shows `sum(n)` *fits* the formation, not that each unit is separately instantiated. "Slots consumed" and "units spawned" are indistinguishable here. * It does **not** close the 387-vs-~300 gap in [roster-to-craft-link](../roster-to-craft-link.md). Σ`n` over all of Stage 02 is 387 against 296–300 live craft. That count was measured mid-mission after kills, and squadrons deploy across phases, so the two are not comparable as they stand — but the earlier note rejected `n = 387` as *the* craft count on the assumption that everything deploys at once, and that assumption is still untested. * ✅ The **key derivation is no longer ❔**: the "second hash function" is [`tag_hash`](idxd-tag-hash.md), recovered since this was written. Record keys and field keys are both `tag_hash` of their own name — 6960 / 6960 field keys across all 28 `UnitGroup` tables, 0 matching `name_hash`.