# Understand a copied reference

Copy a comparison deliberately, preserve its manual provenance and keep earlier checks.

Source: https://help.smartfact.ai/matchbench/guides/copied-reference

Audience: Operator

## Understand a copied reference

1. **Start a comparison**

   Start a comparison.

   Use a known reference and check each label separately. These practice values are synthetic. An exact match is not a physical contents or optical approval.

2. **Keep every leading zero**

   Keep every leading zero.

   Enter the complete reference. MatchBench preserves each character exactly, including spaces and leading zeroes.

3. **Move on to checking labels**

   Move on to checking labels.

   The reference stays fixed until you deliberately change it. Each submitted comparison stays in history.

4. **Find the missing leading zeroes**

   Find the missing leading zeroes.

   The value 17 differs from 000017. These are exact strings, not interchangeable numbers.

5. **Review every retained check**

   Review every retained check.

   Review the newest check first, with its original reference and recorded entry source. A correction does not delete the earlier observation.

6. **Deliberately copy a value as the reference**

   Deliberately copy a value as the reference.

   Copying an earlier comparison creates another reference group. The new reference is recorded as manual, never as a fresh physical scan.

7. **Check the copied reference**

   Check the copied reference.

   The copied reference is now 17. This match belongs to its new group; the earlier 17 mismatch against 000017 is still retained.

8. **Review every retained check**

   Review every retained check.

   Review the newest check first, with its original reference and recorded entry source. A correction does not delete the earlier observation.

[Watch or practise this chapter](https://help.smartfact.ai/matchbench/demo?guide=copied-reference&chapter=copied-reference)