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

# arc:set

> Use the arc:set keyword to set a value on an attribute in ArcScript.

export const siteNameShort = "Arc";

Use the `arc:set` keyword to set a value on an attribute. If an attribute is set in an item that does not exist, the item is automatically created.

You have two ways to set a value using `arc:set`. You can set the **value** parameter or, for large values that are multi-line and complex, you can set the value using the scope of the keyword itself.

## Parameters

* **item**: Specify the item in which the attribute is set. If an item is not specified, the default item is used.
* **attr**: The name of the attribute. You can also specify the item using dot notation (for example, `item.prefix:attr`).
  * A complete attribute name has both a prefix and an attribute name, but the prefix is not required.
  * Attributes can also be denoted as an array by using a hash (`#`). This means that the array can contain more than one value, where each value can be referred to using 1-based indexing. For example, `attr="myitem.myattribute#2"` refers to the second value in the `myattribute` attribute.
* **value**: The value to assign to the attribute. If this parameter is not provided, the entire body of the `arc:set` keyword is used as the value. This is convenient when setting long or multi-line values.
* **copyfrom**: The attributes from the item specified in this parameter are copied to the item specified by the **item** parameter.

## Control Attributes

None

## Example

Use the scope of the keyword to set a value to the message attribute of the item named `input`:

```xml theme={null}
<arc:set item="input" attr="message">
  Dear [name],
  You have won a cruise trip to Hawaii.
  Please confirm your acceptance by [date].
  Thanks, [sales]
</arc:set>
```

## See Also

* [arc:unset](./op-arc-unset): Remove an attribute from an item.
* [arc:setm](./op-arc-set-m): Set multiple attributes with only one keyword.