> ## 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.

# Viewer variables

**Viewer Variables** enable dynamic content customization by replacing placeholders with real-time values for each **Viewer**. These variables can be used in **text fields, data providers, rules, filters, and other elements**, ensuring that displayed content is specific to each Viewer without requiring separate presentations.

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## **Managing Viewer Variables**

### **System Management (Administrator Level)**

* Viewer Variables are created in **PADS4 System Management**.
* Each variable has a **default value** assigned.
* These variables apply to all Viewers unless overridden.
* Users **cannot add or remove variables** through **PADS4 Agent**.

### **PADS4 Agent (User Level)**

* Viewer variables can be **modified** via **PADS4 Agent (Server tab)**.
* Changes made here **overwrite** the default values set in **System Management**.

### **Viewer Options (Local Adjustment)**

* The **Viewer Options window** in the **PADS4 Viewer** application allows **local adjustments**.
* These changes **override both System Management and PADS4 Agent settings**.

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## **Using Viewer Variables**

### **How Viewer Variables Are Identified**

* A Viewer Variable is written as `#VariableName#`.
* Example: `#Store Name#`.

### **Using Viewer Variables in Text Elements**

* Example:
  * **System Management:** `#Store Name# = New York Health`
  * **Text Element:** `Welcome to #Store Name#!`
  * **Displayed Output:** `Welcome to New York Health!`

This method allows **one presentation to be used across multiple locations** while dynamically adjusting text.

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## **Where Can Viewer Variables Be Used?**

### **Text-Based Fields**

* Playlist text content.
* Rule conditions.
* Property bindings.
* Data provider connections.

### **Data Providers**

* Used in **sorting, filtering, expressions, file references, parameters, SQL queries**.

### **Automation Use Cases**

* **Store Size Filtering:**
  * If a store has a **Viewer Variable for size** (`L, XL, XXL`), only products relevant to that size are displayed.
* **Location-Based Content:**
  * A **GPS-based Viewer Variable** allows **location-specific maps or ads** to be displayed.
* **Single Presentation for Multiple Viewers:**
  * Instead of creating multiple presentations, **one presentation can be used with Viewer Variables** to change **store names, addresses, or promotions dynamically**.

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## **When NOT to Use Viewer Variables**

* **For continuous real-time updates** (e.g., rapidly changing stock prices).
* In these cases, a **data provider** should be used instead.

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## **When Are Viewer Variables Updated?**

### **Inside the Data Source**

* When the **Viewer retrieves data**, the **variables are replaced immediately**.
* If the **data provider updates**, the **new values are applied**.

### **In Data Providers**

* If a **Viewer Variable** is used in **filters, sorting, or queries**, it is **replaced at the start of data retrieval**.
* If a data provider **updates once per hour**, **Viewer Variables only update after the next read cycle**.

### **In Presentations**

* When a **presentation loads**, **Viewer Variables in elements (text, images, videos) are replaced**.

### **In Rules**

* **Viewer Variables in rules** are replaced **only when the rule is checked**.
* **Rule checks do not trigger automatically** if a Viewer Variable changes.

### **In Property Bindings**

* If a **data provider updates on a set interval**, the **newest Viewer Variable values replace the old ones**.
* However, changing a Viewer Variable **does not force the data provider to refresh**.

### **In Playlists**

* If the **playlist contains only one item**, the **Viewer Variable is replaced only once** (it does not update).
* If **playlist alternation is enabled**, the **Viewer Variable is replaced with new values after each interval**.

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## **Key Benefits of Viewer Variables**

* **One presentation can be used across multiple locations**, reducing duplication.
* **Automated content personalization**, such as store names and locations.
* **Works seamlessly with data providers, filters, and rules**.
* **Efficient updates without redesigning presentations**.