re: the 'A' route kind names the objective squadrons and predicts the whole OB trajectory

Pure static, from Route_S02.tbl.  Only THREE routes in the entire stage are kind
'A', all in phase 1 -- ADT102, ADT107, ADT113 -- and every one is a
UN_e010_ADAN_Attacker_S squadron of n=4.  The fourth phase-1 e010 squadron,
ADS151, is kind 'F'.

Their first-keyframe times are t=0, t=120 and t=210, so counting only the 'A'
squadrons predicts the counter exactly: 004 at entry, 008 at t=120, 012 at t=210,
and never above 012 in phase 1.  That is what every run has shown -- starting
value, step size and ceiling all fall out of the disc with nothing fitted.

It also explains the two awkward observations: the fifteen-minute hold at 012 (all
'A' squadrons arrived, and those kills were turrets), and why 016 never appeared.
The earlier prediction of a 016 cap is WITHDRAWN: ADS151 is an F route and is not
counted, so the ceiling is 12.

Kept 🟡: "A = marked attack objective" is inference from three routes in one
stage, consistent with the mission dialogue and with A appearing only in early
phases, but the letter's meaning is not proven and the kill test is still unrun.

docs/re/ob-counts-marked-attackers.md

@@ -105,6 +105,58 @@ counter's step of four is a real per-squadron member count. ✅ on that point: t
 `16 / 4` mean is replaced by a measured per-group fact, and the coincidence the
 caveat feared (5/5/3/3) is ruled out.
 
+## ✅✅ The `A` route kind names the objective squadrons — and it predicts the whole trajectory
+
+Route names carry a **kind** suffix (`Route_<sq>_p<phase><kind>`) whose meaning
+[stage-mission-tables.md](structures/stage-mission-tables.md) lists as ❔. In
+Stage 02 the distribution is lopsided:
+
+| phase | A | B | F | M | S |
+|---|---|---|---|---|---|
+| 1 | **3** | — | 16 | — | 18 |
+| 2 | — | — | 15 | — | 22 |
+| 3 | — | — | 13 | 11 | 22 |
+
+**Only three routes in the whole stage are kind `A`, all in phase 1** —
+`ADT102`, `ADT107`, `ADT113`. Every one is a `UN_e010_ADAN_Attacker_S` squadron
+of **n = 4**. (The fourth phase-1 `e010` squadron, `ADS151`, is kind `F`.)
+
+Their first-keyframe times, read from the same table:
+
+| squadron | kind | n | arrival |
+|---|---|---|---|
+| `ADT102` | **A** | 4 | **t = 0** |
+| `ADT107` | **A** | 4 | **t = 120** |
+| `ADT113` | **A** | 4 | **t = 210** |
+| `ADS151` | F | 4 | t = 0 |
+
+Counting only the `A` squadrons gives a complete predicted trajectory:
+
+| mission time | arrived `A` craft | predicted counter |
+|---|---|---|
+| 0 | 4 | **004** |
+| 120 | 8 | **008** |
+| 210 | 12 | **012** |
+| — | — | **never exceeds 012 in phase 1** |
+
+**That is exactly what every run has shown**: the counter is `004` at flight
+entry, steps to `008` and then `012` within the first three to four minutes, and
+has never been observed above `012`. All three features — the starting value, the
+step size, and the ceiling — fall out of the disc with nothing fitted.
+
+It also explains the two results that looked like problems:
+
+* The **fifteen-minute hold at `012`** — after t = 210 every `A` squadron has
+  arrived, so the counter can only fall, and that run's kills were turrets.
+* **`016` never appeared.** An earlier version of this note predicted a cap of 16
+  from four squadrons; that prediction is **withdrawn**. `ADS151` is an `F` route
+  and is not counted, so the ceiling is 12.
+
+🟡 The reading of `A` as "the marked attack objective" is inference from a
+three-route sample in one stage. It is strongly consistent with the mission
+dialogue ("the attackers with the orange markers") and with `A` appearing only in
+early phases corpus-wide, but the letter's meaning is not proven.
+
 ## ❌ A premise of this note was WRONG — ADN110/111/112 are TURRETS
 
 This note said the polled squadrons ADN110, ADN111 and ADN112 arrive at t=170 and