## Revision schemes define how part revisions are named

Revision schemes define how part revisions are named (for example, alphabetic A, B, C or numeric 1, 2, 3). You can configure multiple schemes and set one as the default.

## Revision scheme format

A revision scheme’s format defines the sequence of characters a revision can use. You build it from segments and separators:

- Click **A–Z** to add an alphabetic segment (A, B, C, and so on).
- Click **0–9** to add a numeric segment (1, 2, 3, and so on).
- To place a separator between segments, type a single character in the **Separator** field and click **Add**.

A format must include at least one numbering segment ( **A–Z** or **0–9**).

## Add a revision scheme

1. In ION, go to **Settings > Supply Chain > Parts**.
2. In the **Part Revision Schemes** section, fill in the new scheme form:
   - Enter a **name** for the scheme.
   - Build the **format**, as described in [Revision scheme format](https://docs.firstresonance.io/administration/supply-chain-settings/configure-part-revision-schemes#revision-scheme-format).
   - Optional: Turn on **Overflow** to continue the sequence past the last defined value.
   - Optional: Turn on **Default** to make this the default scheme.
3. Click **Create Scheme**.

## Edit a revision scheme

1. In ION, go to **Settings > Supply Chain > Parts**.
2. In the **Part Revision Schemes** section, click a scheme to expand it.
3. Update the name, **Allow overflow** setting, or **Default** flag as needed.

## Delete a revision scheme

1. In ION, go to **Settings > Supply Chain > Parts**.
2. In the **Part Revision Schemes** section, click the trash icon on the scheme’s row.