# Mappable parameters

Mappable parameters can either be filled in by the user or mapped from previous modules.

Mappable parameters use [parameters syntax](https://developers.make.com/custom-apps-documentation/block-elements/parameters).

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<div align="left"><figure><img src="https://1562974717-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FNS0mCBwODiYtOVXjc6qf%2Fuploads%2Fgit-blob-919440800fae36c40a437b6eb636a7a5b5002bfb%2Fmappableparameters_blocks.png?alt=media" alt="" width="548"><figcaption></figcaption></figure></div>
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```json
[
	{
		"name": "email",
		"type": "email",
		"label": "Email address",
		"required": true
	},
	{
		"name": "name",
		"type": "text",
		"label": "Name",
		"required": true
	},
	{
		"name": "newsletter",
		"type": "boolean",
		"label": "Send newsletter?",
		"default": false,
		"required": true
	},
	{
		"name": "size",
		"type": "select",
		"label": "T-Shirt size",
		"options": [
			{
				"label": "S",
				"value": "s"
			},
			{
				"label": "M",
				"value": "m"
			},
			{
				"label": "L",
				"value": "l"
			}
		]
	}
]
```

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You can use [Remote Procedure Calls (RPCs)](https://developers.make.com/custom-apps-documentation/app-components/rpcs/dynamic-fields-rpc) to generate parameters dynamically.

Learn more about [best practices regarding mappable parameters](https://developers.make.com/custom-apps-documentation/best-practices/input-parameters/mappable-parameters).