> ## Documentation Index
> Fetch the complete documentation index at: https://docs.drpn.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Schema model

> Schema structure, lifecycle stages, and change control.

A schema is a reusable contract for source data shape.

## Schema design

* Use names that describe the source and record type.
* Keep field names stable across runs.
* Represent identifiers as strings unless arithmetic is required.
* Represent money and quantities consistently.
* Document fields that are derived or normalized.

## Schema lifecycle

| Stage    | Action                                                          |
| -------- | --------------------------------------------------------------- |
| Draft    | Create the initial schema from a known source sample.           |
| Validate | Run a small reconciliation or parse test.                       |
| Adopt    | Use the schema for recurring reconciliation runs.               |
| Revise   | Update only when the source shape or business contract changes. |

## Change control

Changing a schema can change future run output. When a schema change affects comparison behavior, record why it changed and which reconciliation runs use the revised schema.

***

To create a schema in Darpan, see [Create a schema](/guides/create-schema).