a304df1e50
Reading the docs first paid: unit-substructure-records already had UN_e001_ADAN_Elan_EX4 and arsenal-item-weapon-chain already had _T_EX5_el, so last pass's "the only two _EX5 names on the disc" was too narrow. Withdrawn and replaced by a census. Every name ENDING in _EX<digit> across all 41 archives, taken from parsed IDXD record names, field names and string values (never a raw byte scan): 26 names, two digits only - _EX4 (7 units, 6 ADAN + 1 TCAF) and _EX5 (4 TCAF units + 1 weapon), each with a UnitName_/WeaponCannonName_ twin. The stage join is exact. _EX4 appears only in tables S27 declares (EnumUnit_S27.tbl, UnitGroup_S27.tbl); _EX5 only in S28's (EnumUnit_S28.tbl, UnitGroup_S28.tbl, EnumWeapon_EX5.tbl); the other 20 stages have neither. The challenge missions are S24-S29 in order, so S27 is challenge #4 and S28 is challenge #5: _EXn names the n-th challenge ("EXtra") mission's bespoke variants. S28 declares both schemes at once - EnumUnit_S28.tbl by stage number, EnumWeapon_EX5.tbl by challenge index, for the same mission. Refuted: _EXn is not the Extra0n numbering. There are four Extra slots but _EX5 exists, and under that reading Extra04 would be S29, which has no _EX assets. Makes available but does not settle result-screens' open "what does EX_ mean": "the challenge-mission debriefing" fits its evidence that the EX_ twin drops overview_rank/overview_medals. Recorded there as a reading, not adopted. All fifteen artefacts byte-identical.