Slicer  4.13
Slicer is a multi-platform, free and open source software package for visualization and medical image computing

VolumeRendering → SubjectHierarchy Relation

File in Modules/Loadable/VolumeRenderingIncludes file in Modules/Loadable/SubjectHierarchy
SubjectHierarchyPlugins / qSlicerSubjectHierarchyVolumeRenderingPlugin.hWidgets / qSlicerSubjectHierarchyAbstractPlugin.h