> For the complete documentation index, see [llms.txt](https://docs.b2ihealthcare.com/snow-owl-authoring-platform/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.b2ihealthcare.com/snow-owl-authoring-platform/browsing-and-searching/snomed-ct-view/sub-hierarchy.md).

# Sub-hierarchy

You can omit irrelevant high-level concepts or sibling concepts, by setting the concept as a root. You can do it either by using the corresponding toolbar button or by right-clicking the concept and selecting ![](https://snowowl.atlassian.net/wiki/download/thumbnails/611025384/worddavd0e0d213fcb2280aa08e95c188b23bb3.png?version=1\&modificationDate=1578324616000\&cacheVersion=1\&api=v2\&width=16) *Set as root concept*. To display the full terminology again, use the ![](https://snowowl.atlassian.net/wiki/download/thumbnails/611025384/worddav71cfa5ae097fc33ab92692a745fae747.png?version=1\&modificationDate=1578324616653\&cacheVersion=1\&api=v2\&width=16) *Return to root concept* toolbar button.

![Setting a Concept as Root](/files/JtWysAgkjhoiXyXlvJdo)

The ![](https://snowowl.atlassian.net/wiki/download/thumbnails/611025384/worddav960ab9d79c2a82919f01e1fecd76842a.png?version=1\&modificationDate=1578324618360\&cacheVersion=1\&api=v2\&width=16) *Collapse all nodes* button closes the low-level nodes in the view. If a concept is set as a root, all nodes within the sub-hierarchy are collapsed and only the root concept and its children are displayed. If you expanded nodes in the full terminology, the view will reset to the default state displaying only the top-level concepts

![Nodes Collapsed](/files/opAElL2k5Q2NaWatTRNY)


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