# How does SubjectHierarchy Plugins works in Slicer
**URL:** https://discourse.slicer.org/t/how-does-subjecthierarchy-plugins-works-in-slicer/8354
**Category:** Development
**Created:** [September 10, 2019, 5:12am UTC](https://discourse.slicer.org/t/how-does-subjecthierarchy-plugins-works-in-slicer/8354 "2019-09-10T05:12:33Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@mikecsu](https://discourse.slicer.org/u/mikecsu)
#### Post date: [September 10, 2019, 5:12am UTC](https://discourse.slicer.org/t/how-does-subjecthierarchy-plugins-works-in-slicer/8354/1 "2019-09-10T05:12:33Z")
Operating system:win10
Slicer version:slicer 4.10.0
Expected behavior:
Actual behavior:
Hi,everyone. I am learning the slicer source code for simplifying some operations in Slicer. But i have trouble in understanding the SubjectHierarchy Plugins, can anyone explain it ?
Any help would be appreciated.
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### Author:  [@lassoan](https://discourse.slicer.org/u/lassoan)
#### Post date: [September 11, 2019, 2:45pm UTC](https://discourse.slicer.org/t/how-does-subjecthierarchy-plugins-works-in-slicer/8354/2 "2019-09-11T14:45:28Z")
Subject hierarchy plugins can be used to add custom icon, override default actions (such as show/hide), or define new actions in the right-click menu.
You can implement these plugins in either C++ or Python. There are many examples in Slicer core: download source code of Slicer and search for “SubjectHierarchyPlugins” folders.
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### Author:  [@cpinter](https://discourse.slicer.org/u/cpinter)
#### Post date: [September 11, 2019, 2:51pm UTC](https://discourse.slicer.org/t/how-does-subjecthierarchy-plugins-works-in-slicer/8354/3 "2019-09-11T14:51:49Z")
I suggest also reading the Information for Developers section on this page
[https://www.slicer.org/wiki/Documentation/Nightly/Modules/Data](https://www.slicer.org/wiki/Documentation/Nightly/Modules/Data)