> ## Documentation Index
> Fetch the complete documentation index at: https://docs.pads4.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Cluster related Viewer Variables

When Clusters are created in **PADS4 CTRL Center**, **system-defined Viewer Variables** are automatically available. These variables help control **content distribution** across Clustered Viewers based on their **position** and **availability**.

## **System-Defined Cluster Viewer Variables**

| **Variable**           | **Description**                                                                                                                                                                   |
| ---------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| **ClusterWidth**       | Total number of **horizontal** Viewers in the Cluster.                                                                                                                            |
| **ClusterHeight**      | Total number of **vertical** Viewers in the Cluster.                                                                                                                              |
| **HorizontalPosition** | Defines the **current page number** that should be displayed based on **viewer availability** in a **horizontally aligned** Cluster. Adjusts dynamically when Viewers go offline. |
| **VerticalPosition**   | Defines the **current page number** that should be displayed based on **viewer availability** in a **vertically aligned** Cluster. Adjusts dynamically when Viewers go offline.   |
| **IndexX**             | The **designed horizontal position** of this Viewer within the Cluster.                                                                                                           |
| **IndexY**             | The **designed vertical position** of this Viewer within the Cluster.                                                                                                             |

## **Example Cluster Configuration**

The example below illustrates a **2x2 Cluster** with **4 Viewers**.

| **Cluster Viewers**  | **Horizontal Position** | **Vertical Position** | **IndexX** | **IndexY** |
| -------------------- | ----------------------- | --------------------- | ---------- | ---------- |
| **Cluster Viewer 1** | 1                       | 1                     | 0          | 0          |
| **Cluster Viewer 2** | 2                       | 3                     | 1          | 0          |
| **Cluster Viewer 3** | 3                       | 2                     | 0          | 1          |
| **Cluster Viewer 4** | 4                       | 4                     | 1          | 1          |

## **How These Variables Work in a Cluster**

1. **Dynamic Page Assignment**:
   * If **Viewer 2 goes offline**, **Viewer 3 or Viewer 4 will automatically take over its content**.
   * If a Viewer is **removed or disabled**, PADS4 **automatically reassigns the correct page positions**.
2. **Intelligent Content Distribution**:
   * **HorizontalPosition** ensures content is **evenly distributed** when a Viewer is removed.
   * **VerticalPosition** helps determine which **upper Viewers' content moves down** if a screen fails.
3. **Flexible Layout Customization**:
   * **IndexX/IndexY** allow **precise control** over the **placement of Viewers** within a Cluster.
   * Adjustments can be **rule-based**, ensuring smooth **failover handling**.

## **Practical Use Cases**

* **Airport Flight Information Displays**: Ensures **continuous flight listings** across multiple screens.
* **Menu Boards in Restaurants**: Automatically shifts menu content if one screen **fails**.
* **Retail Digital Signage**: Prevents **content gaps** and **adjusts layout dynamically**.

By utilizing these **Cluster Viewer Variables**, you can **optimize digital signage layouts**, **reduce downtime**, and **automate content distribution** across your PADS4 system.