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

# Core Event Properties

> Essential properties for tracking events — value, currency, transactionId, and orderName.

Core properties are the foundational fields used across most tracking events. These are typically required or strongly recommended for proper attribution and reporting.

## Properties

<CardGroup cols={2}>
  <Card title="value" icon="coins" href="/pixel/events/properties/value">
    Monetary value of the event.
  </Card>

  <Card title="currency" icon="dollar-sign" href="/pixel/events/properties/currency">
    ISO 4217 currency code.
  </Card>

  <Card title="transactionId" icon="fingerprint" href="/pixel/events/properties/transaction-id">
    Unique order identifier.
  </Card>

  <Card title="orderName" icon="hashtag" href="/pixel/events/properties/order-name">
    Human-readable order number.
  </Card>
</CardGroup>

## Quick Reference

| Property        | Type   | Required                          | Description                                    |
| --------------- | ------ | --------------------------------- | ---------------------------------------------- |
| `value`         | number | Yes for purchase, lead, subscribe | Monetary value of the event                    |
| `currency`      | string | Yes (when value is set)           | ISO 4217 currency code (USD, EUR, GBP)         |
| `transactionId` | string | Yes for purchase/refund           | Unique order identifier                        |
| `orderName`     | string | No                                | Human-readable order number shown to customers |

## Example

```javascript theme={null}
window._upstack('track', 'purchase', {
  value: 149.99,
  currency: 'USD',
  transactionId: 'ORD-2026-001',
  orderName: '#1042',
  items: [/* ... */]
});
```

<Note>
  For Purchase events, `value` should match the order total you want reported to ad platforms.
</Note>