# Control Block
## Description
* Control blocks are used to distinguish standard HTML input elements from Sodium input elements in a [Form File](/sodium_documentation/language-reference/program-structure/form-file.md).
* Control blocks cannot be nested.
* Sodium CSS rules only applies to input elements in Control Block and Data Block elements.
* Sodium event/triggers only applies to input elements in Control Block and Data Block elements.
* Control block's name is mandatory and must be unique in a form file.
## Declaration
```
```
## Properties
### control-block-name property
**Mandatory :** yes\
**Unique :** yes\
**Data Type :** char\
**Default Value:** -\
**Predefined Values Allowed:** -
## Triggers
None
## Allowed Inner HTML Elements
Standard HTML Tags\
[Inputs](/sodium_documentation/language-reference/tags/inputs.md)\
[Tree Element](/sodium_documentation/language-reference/tags/tree-element.md)
## Built-in Functions
---
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