# C751 — First twenty-step explanatory checkpoint

## Question

What generalizes, and what frame must remain explicit?

## Inputs

```json
{
  "regular_frame": "common full430 comparison",
  "native_Cainan": {
    "MT": "OFF",
    "LXX": "ON",
    "SP": "OFF"
  }
}
```

## Sources

```json
[
  "C733–750"
]
```

## Opened utc

2026-09-28T01:53:05.590400+00:00

## Results

```json
{
  "checkpoint": {
    "path": "deliverables/490d_Chronological_Families_Checkpoint_C751.md",
    "sha256": "6865f3a55c73e0a3b0d2d6964597a26f6c4cbe5a46484ffd85a542ca18784464",
    "bytes": 1313
  },
  "SP_frame_check": {
    "full430": 8982,
    "native215": 9197
  }
}
```

## Finding

The comparison now has an explicit frame and a whole-field explanation. Proceed with the residual operator rather than surveying more endpoints.

## Reassessment

Derive the complete finite rounding defect law.

## Checks

```json
{
  "SP_frame": true,
  "twenty_steps": true
}
```

## Closed utc

2026-09-28T01:53:05.590673+00:00

## Record provenance

Exact record hash: `5422c036ee98a0217ffe567508da299e8cd2ce859c0f3c36a4c6a0cfe7769953`

Source journal: `Research_Cycles/C0732_C0831/journal.json`