# Creating a New Field Mapping

A field mapping connects an existing standard Aisera field to a field in your Data Source. To create a field mapping. To create a new field mapping navigate to **Settings > Data Sources** in the Aisera Admin UI and select the Data Source you would like to create a custom field mapping for. Click **New Field Mapping** at the bottom of the **Data Source Details** page to open the **New Field Mapping** window. 

### Aisera Field

A dropdown of existing Aisera fields available for the current content type. Fields already mapped for this Data Source will not appear in the list.

### Content Type

Determines which content type the field applies to. Only appears when the selected content type has subtypes. Defaults to the content type you are currently working with.

### Value Generation Type

Controls how the fields value is populate. Select one of the following:

* **Field Mapping** - Maps directly to a field in the Data Source. Insert the corresponding  field name or [JSONPath expression](https://www.rfc-editor.org/rfc/rfc9535) in the \<Application Name> Field that appears.
* **Derivation Rule** - Populates the field using one or more derivation rules. Click **Add a Derivation Rule** to open the [New Derivation Rule](https://docs.aisera.com/aisera-platform/adding-data-to-your-tenant/data-ingestion/field-mappings/derivation-rules) window.

### Date format

Only visible when the selected Aisera field is a date/time field. Enter the date format as an ISO 8601 string so the value can be parsed correctly.

### Fixed Value

Only visible when the Value Generation Type is set to Field Mapping and the selected field is not a date/time field. Enter a static fallback value to use when no external value is present.

### Outbound Field

The [JSONPath expression](https://www.rfc-editor.org/rfc/rfc9535) for the path in the external system to write data back to. When the Aisera Platform sends data to the external system, it will use this path instead of the **\<Application Name> Field** path. If left empty, the **\<Application Name> field** path is used for both reading and writing.

### Anonymization Rule

An optional JSON configuration defining how Personally Identifiable Information (PII) in this field's values should be detected and anonymized during ingestion. The Aisera Platform uses Microsoft Presidio anonymization ending. See the [Presidio Anonymizer documentation](https://microsoft.github.io/presidio/anonymizer/) for configuration details.