# Field mappings
source: https://developer.mastercard.com/commercial-event-notifications/documentation/parameters/fieldmappings/index.md

This resource allows you to retrieve a list of fields that you can use to filter the messages for [supported events](https://developer.mastercard.com/commercial-event-notifications/documentation/index.md). When creating a subscription, use fieldmappings to define conditions in the specifications array for the API.
Only if the conditions are met will the API create notifications for your subscription.

If you do not specify any field mappings in a subscription, then notifications are created for all supported events that occur for your virtual cards.

## Try it Out {#try-it-out}


API Reference: `GET /fieldmappings`