# C682 — Separate translation from opening

## Question

Can one coordinate rule explain both the120 construction and the2940 closure?

## Inputs

```json
{
  "changes": {
    "translate80": [
      80,
      80
    ],
    "open10": [
      10,
      -10
    ],
    "open5": [
      5,
      -5
    ]
  }
}
```

## Sources

```json
[
  "C677,C680,C681"
]
```

## Opened utc

2026-09-28T01:12:36.616587+00:00

## Results

```json
{
  "effects": {
    "translate80": {
      "center_change": 80,
      "width_change": 0
    },
    "open10": {
      "center_change": 0,
      "width_change": 20
    },
    "open5": {
      "center_change": 0,
      "width_change": 10
    }
  },
  "general_rule": "delta_c=(delta_U+delta_L)/2; delta_w=delta_U−delta_L"
}
```

## Finding

Center and width provide a common language for two different mechanisms: translation moves the center while retaining width; symmetric opening widens the body while retaining center. The new sources instantiate both, so no single undifferentiated date shift explains the family.

## Reassessment

Continue the admitted alternating ladder across the BC/AD boundary using civil elapsed time.

## Checks

```json
{
  "translation": true,
  "opening": true,
  "final": true
}
```

## Closed utc

2026-09-28T01:12:36.616956+00:00

## Record provenance

Exact record hash: `a351a7a5c3fee6a9423402b95d80d68802fbbf922aa1712a0a73b450b4762a68`

Source journal: `Research_Cycles/C0632_C0731/journal.json`