This archive tracks four layers. A record present in 1 of them (M41) is silent in the rest, and says so.
The Horus HeresyM30–M31
[RECORD LOST]
No record for this location in The Horus Heresy.
Age of the ImperiumM32–M40
[RECORD LOST]
No record for this location in Age of the Imperium.
The 41st Millenniumpre-Rift
contested
Imperial hive world invaded by the Crimson Slaughter in the 13th Black Crusade
A hive world of the Imperium whose hive cities are so enormous they astonish even a seasoned Space Marine; long before, the Crimson Sabres Chapter fought eldar pirates raiding its hive spires. In 999.M41, during Abaddon the Despoiler's 13th Black Crusade, the same warriors return as the fallen Crimson Slaughter, given the world to strike: they land on its grey ash plains and assault the Imperial Guard trench lines, artillery and tank companies, Cadian Shock Troops and the Cadian 44th Armoured among them, that guard its continent-sized hives. How the battle ends for the book's people is in Steel Daemon's spoiler.
Era Indomituspost-Rift
[RECORD LOST]
No record for this location in Era Indomitus.
Position
Map frame: 665.1, 898.2 in the archive's 0–1000 disk space (core at 500, 500).
Distance from the core: 431 units ≈ 45.9k light years, south-east of the galactic core.
Height above the disk plane: -7.8 units — invented thin-disk jitter, deterministic per record. No published source gives any location a z coordinate.
System: Regallus System
Books set here
1 title in the reading tracker touches this record, 1 of them as a primary location. Titles link out to the tracker.
Every fact in this record, and where it came from. Editorial derivations say so.
identityhigh
wh40k.lexicanum.com/wiki/Regallus (read directly in a browser on 2026-10-02): 'a Hive World of the Imperium'; the Crimson Sabres fought eldar pirates raiding its hive spires (citing Steel Daemon, Part 1); 'The planet's Hives were enormous, astonishing even a seasoned Space Marine' (citing the Crimson Slaughter codex supplement); invaded by the Crimson Slaughter in the 13th Black Crusade (citing the codex and Steel Daemon, Parts 1-3). https://wh40k.lexicanum.com/wiki/Battle_of_Regallus: 999.M41, the 13th Black Crusade; Imperial Guard 'including Cadian Shock Troopers' (citing Steel Daemon, Part 1) and PDF against the Crimson Slaughter. https://wh40k.lexicanum.com/wiki/Steel_Daemon_(Novella): Black Library's description, 'Descending upon the planet Regallus'. NAME-COLLISION CHECK: no index record uses the name, and Lexicanum full-text search for 'Regallus' (11 results) finds only this world and its battle.
segmentumhigh
null: Lexicanum's infobox gives segmentum, sector, subsector and system as Unknown (category 'Segmentum Unknown'), and no permitted source gives any geography. That the 13th Black Crusade struck around the Cadian Gate does not place the world: the Crusade's warbands attacked across Eyespace, and nothing says Regallus is in the Cadian Gate.
gposlow
inferred: the world is NAMED but canon never locates it, so the record claims no segmentum and sits on the unsurveyed rim at the generator's rim_xy('regallus') = [665.1, 898.2] (the function in build_locations.py evaluated on its own, which reproduces rezlan-vi [846.3, 207.9] and gavaine [91.0, 653.3]; the script itself was not run). The position carries no information and must not be read as one. Z -7.8 is the zPolicy value (compute-z.mjs regallus 665.1 898.2).
classmedium
'hive' from what the sources say it LOOKS like: 'mighty continent-sized hive cities', 'the tangled inner hive', hab-blocks and long avenues lined with towering statues, set among grey ash plains (Lexicanum Battle_of_Regallus, from the codex), and hive cities 'enormous, astonishing even a seasoned Space Marine' (Lexicanum Regallus). Here the Lexicanum tag 'Hive World (former)' and the look agree. 'dead' was refused: the world is laid to ruin only by the end of the battle, and the one book set there is set during it. No era override is authored: the record's class already says hive, and the m41 status avoids the words the status-prose rule repaints as 'dead'.
erasmedium
m41 only: the Battle of Regallus is dated 999.M41, in the 13th Black Crusade (Lexicanum Battle_of_Regallus), the era Steel Daemon is filed in, as The Fall of Cadia and Daemonbreaker are. Allegiance 'contested': an Imperial world under Chaos invasion through the book. Lexicanum gives its later affiliation as 'Chaos, formerly Imperium'; no book on the shelf is set there after the battle, so no indomitus era is recorded and the outcome is kept in the book's spoiler.
systemIdlow
editorial: 'regallus', the world's own name; Lexicanum gives the system as Unknown and no source names a star or another world. The survey systems/regallus.json is ONE WORLD and TRUNCATED.