# Constraint Control

:::info
This functionality is available in the PRO Edition only.
:::

A complex control used to set [time constraints for Gantt tasks](guides/auto-scheduling.md#timeconstraintsfortasks).

![Constraint control](/img/constraint_control.png)

~~~js
gantt.config.lightbox.sections = [
    { name:"description", height:38, map_to:"text", type:"textarea", focus:true},
    { name:"constraint", type:"constraint" },  /*!*/
    { name:"time", type:"duration", map_to:"auto" }
];
~~~


[Auto-Schedule From Project Start & Constraints](https://docs.dhtmlx.com/gantt/samples/02_extensions/19_constraints_scheduling.html)


## Initialization

To add the **constraint** control to the lightbox, follow the steps below:

1. Add a section to the lightbox configuration:

~~~js
gantt.config.lightbox.sections = [
    { name:"description", height:38, map_to:"text", type:"textarea", focus:true},
    { name:"constraint", type:"constraint" },  /*!*/
    { name:"time", type:"duration", map_to:"auto" }
];
~~~

2. Set a label for the section:

~~~js
gantt.locale.labels.section_constraint = "Constraint";
~~~


[Auto-Schedule From Project Start & Constraints](https://docs.dhtmlx.com/gantt/samples/02_extensions/19_constraints_scheduling.html)


## Properties

The following properties are mostly important and commonly set for the **constraint** control (see the full list [here](api/config/lightbox.md)):

- **name** - (*string*) the section name 
- **type** - (*string*) the type of the [section control](guides/default-edit-form.md#lightboxcontrols)