# Define render parameters Add fields, choose types, set defaults, and use Payload to prepare template data. To reuse a template with different data, first declare the fields it accepts. **Parameters** lets you name each field, choose its type, and provide a default value. Start with a simple field, connect it to HTML, then open Payload to inspect the resulting data structure. ## 1. Add a field in Schema Open **Parameters**, select **Schema**, and choose **Add**. Rename the new field to the name you want to use, such as `recipient`. | Type | Suitable data | | --- | --- | | Text | Names, addresses, references, or formatted strings. | | Number | Quantities or numeric values. | | Boolean | `true` / `false`. | | Object | A named group of fields. | | Array | A list of elements with the same structure. | **Color** and **Asset** are prop-only types in the current editor, so they do not appear in the Parameters type list.

Parameters＋ Add

SchemaPayload

recipientText

DEFAULTTembuilder{{ params.recipient }}

Parameters → Add → Schema

## 2. Set Default and Required Enter **Default** on the field card to provide a value when the caller omits the field. The required control in the card header toggles the field’s **Required** status. Use values of the declared type: a Number uses `2`, and a Boolean uses `true` or `false`. The string `"2"` is not a number. An empty string is still a supplied value, not an omitted field. Add a description to explain the value’s purpose, units, or expected format to someone using the template.

Schema

recipient *Text

DEFAULTTembuilder{{ params.recipient }}

DefaultUsed when the field is omitted

RequiredMarks a required field

Name, type, Default, and Required appear on the same field card

## 3. Connect the field to content Each card includes an **EMBED** expression. For `recipient`, insert this into a section’s HTML: ```handlebars

``` `recipient` must match the Schema name. If you rename the field later, update both the HTML expression and the data supplied to the template.

recipientText

DEFAULTTembuilder{{ params.recipient }}

{{ params.recipient }}

Copy the EMBED expression into section HTML

## 4. Get the structure from Payload Switch to **Payload** to inspect the object built from the declared fields and defaults: ```json { "recipient": "Tembuilder", "copies": 2, "showNotes": true } ``` This is the template’s data object. Use the same structure when entering data in **Run**. For API integration, the object belongs in the request’s `parameters` field; see the [Render API reference](/docs/developers/render-reference/) for the request fields and endpoints. For nested fields and lists, continue with [Objects, arrays, and tables](/docs/data/arrays-objects/).

Parameters

SchemaPayload

{ "recipient": "Tembuilder", "copies": 2, "showNotes": true}

Schema → Payload → Run