# VirtualBox bind

With the **VirtualBox bind** trigger, the workflow process starts when a virtual box is associated to a file. A [Virtual Box](/data-mover-1.21/contracts/virtual-boxes.md) is a way to classify and tag files in Data Mover.  

For example, when a workflow template binds a virtual box to a file, an event is emitted and contracts having the **VirtualBox bind** trigger will start. This scenario can occur both with a mediation contract having the VirtualBox bind trigger, and with an output system workflow template where the user specifies in the contract the virtual box to be associated with the file. 

The **VirtualBox bind** trigger requires a virtual box.

**Execution Variable**

When executed, this trigger adds an execution variable named `file`, of type `FileDetail`. Its attributes are set based on the information sent from the event that initiated the trigger. 

For the **VirtualBox bind** trigger, Data Mover provides a set of **system workflow templates** that must be used in output contracts. You can find the complete list on the following page: [Workflow templates for output contracts → Trigger type: VirtualBox Bind](/data-mover-1.21/workflow-templates/system-workflow-templates/workflow-templates-for-output-contracts.md#trigger-type-virtual-box-bind). 


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