# C318 — Typed458 replacement: source and interpretation audit

24 September 2026. Separate source/method review of C318 only.

## Scope and source warrant

File_18 §0.1d rules2,6,10,12 and14 distinguish chronology methods, variant boundaries, SP person-rail locality, regular130 versus cumulative460 Cainan, and membership within a cumulative envelope. §1.1 supplies Terah60 and sojourn215 variant states. §3.1.4 gives same-Gear SP and MT Flood start/close differences650 in the held full430/OFF/Terah0 context and limits ordinary Gear movement before fixed Arphaxad. §3.2.1 supplies SP person stations but gives no MT person-companion permission. §2's restored-Cainan discussion explicitly shows MT Flood2646/2648/2650 with regular Cainan130 and Terah60 opened (lines826–829). The restored final MT contexts are therefore supported states, not invented dates.

File_09 §0.4 rule16 likewise prohibits interchanging regular130 and cumulative460. Rules21 and24 distinguish a seven-year envelope's member labels from operators and generated local coordinates from source rows. §0.5 preserves cumulative versus regular node classes.

For LXX cumulative OFF→ON, the460 action restores the already native Cainan to the theoretical OFF comparison state. It must not be described as adding another460 to a native ON row. Selecting member i+2 is a new member selection within that ON envelope; it is not applying a regular Gear to the cumulative chronology.

## Sign discipline

Write B for a positive BC date number, x=−B for its signed source coordinate, and its reflected endpoint coordinate as −x=B under the inherited convention. A change B→B+δ gives x→x−δ but a reflected endpoint change+δ.

Consequently the cumulative signed route is p_OFF,i→p_ON,i=p−460, then p_ON,i+2=p−460+2. The regular route is described in positive BC numbers, or equivalently reflected coordinates: SP→same-Gear MT subtracts650; restoring regular Cainan adds130; Terah+60 adds60; the next higher Gear adds2. The net reflected change is−650+130+60+2=−458. The unreflected signed MT source has the opposite change. Reporting both routes as−458 is correct only after specifying these different coordinate representations.

Every regular route preserves Flood start versus Flood close. A close remains an event boundary with rail=null; it must not acquire a primary/companion person label during SP→MT comparison. The person rail merely selected which boundary the earlier SP biography used.

## Admissibility and composition status

All intermediate actions through regular Cainan/Terah restoration are within the permitted Noah/Shem/Flood domain. Their endpoints must still be checked against the held source register. The final next-Gear step is admitted only when its source Gear is1 or2. Starting from G3 has no G4 target. Independently, cumulative reindexing i→i+2 fails when it leaves0…7. These are two source-domain failures, not discretionary exclusions designed to improve a harmonic.

The explicit parent tables and rule passages permit the ingredients and authenticate the resulting retained states. I found no statement in the reviewed passages prescribing this exact joint composition, its paired+2 member/Gear selection, or a universal458 action. The source-supported ingredients make the bounded comparison legitimate; they do not establish that the tradition intended this matching recipe. C311's distinction between ingredient, generic comparison warrant and prescribed selector remains applicable.

Scalar agreement650−130−60=460 explains why the two net substitutions can agree once their local+2 selections are made. It does not equate the historical roles of those terms, turn regular Cainan into460, or create a new chronology-wide translation rule. Re-expression of the already identified C287 corners should not be counted as a new independent numerical witness.

## Best subsequent bounded question

After C318, test the necessity of the **paired local+2 selections** with a fixed four-case sensitivity check: retain or omit the cumulative member advance and retain or omit the permitted regular Gear advance, while keeping all other contexts and source boundaries fixed. Ask which17K/2K/15K relationships survive and which depend specifically on the coupled choice. This would expose whether the529 configuration has a structural selector or only a state-qualified successful configuration. No such later sensitivity calculation is performed here.