> For the complete documentation index, see [llms.txt](https://docs.flatredball.com/flatredball/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.flatredball.com/flatredball/glue-reference/states/tunneling-category-variables.md).
# Tunneling Category Variables
### Introduction
State categories automatically create variables in Screens and Entities through generated code. These generated variables can also be accessed in the FRB editor so they can be set on instances, or to assign change events.
### Example - Tunneling a Category
For this example, consider an Entity named StateEntity which has a SizeCategory with three states: Small, Medium, and Large.
Entity with a SizeCategory
This entity generates a variable called CurrentSizeCategoryState which can be accessed in code, as shown in the following code block:
```csharp
private void CustomInitialize()
{
this.CurrentSizeCategoryState = SizeCategory.Large;
}
```
The CurrentSizeCategoryState can be tunneled on the entity which can be useful in a number of situations:
1. To set a default state for the entity
2. To set the state per-instance in the FRB Editor
3. To create events which is raised whenever a state is set to perform custom logic
To tunnel into a variable, drag+drop the category on the Variables folder.
Tunneling to the CurrentSizeCategoryState
The tunneled variable now behaves like any other variable. For example, an event can be added to the variable which is raised whenever the SizeCategory changes.
Adding an Event for tunneled category variables
---
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