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

# Dataset format for system and user prompts

export const plans_0 = "Any"

export const deployments_0 = "Any"

export const data_plane_version_0 = undefined

export const use_case_0 = undefined

<Note>
  **Applies to:**

  * Plan - {plans_0}
  * Deployment - {deployments_0}
  * {data_plane_version_0}
  * {use_case_0}
</Note>

## Summary

**Goal:** Structure dataset rows with varying system and user prompts for multi-model comparison in Playground.

**Features:** Datasets with chat message arrays, Playground model comparison, role-based message formatting.

## Configuration Steps

### Step 1: Structure dataset rows with chat message arrays

Each dataset row should contain an array with system and user messages using role-based formatting.

```text theme={"theme":{"light":"github-light","dark":"github-dark-dimmed"}}
{
  "input": [
    {"role": "system", "content": "You are a helpful assistant."},
    {"role": "user", "content": "What is the capital of France?"}
  ]
}

```

### Step 2: Add rows with varying system prompts

Create multiple rows where system prompts differ while maintaining the same structure.

```text theme={"theme":{"light":"github-light","dark":"github-dark-dimmed"}}
{
  "input": [
    {"role": "system", "content": "You are a creative writer."},
    {"role": "user", "content": "Write a short story."}
  ]
}

```

### Step 3: Enable "Append dataset messages" in Playground

In Playground Advanced settings, enable "Append dataset messages" and set the path to your messages array field (e.g., `input`).

### Step 4: Configure model comparison

Add multiple model configurations in Playground to test each dataset row across all models with their respective system prompts.

## Key Notes

* Each row represents one test case that runs across all configured models
* System prompts are included in the dataset row and vary per input
* All messages in the array (system and user) are appended when using "Append dataset messages"
* Alternative: Save fixed system prompts as reusable custom prompts and store only user content in datasets