| EntityTreeBuildExtensions | Contains methods for building a tree from a source hierarchy. |
| EntityTreeNodeTNode, TItem | Abstract tree node that refines ItemTreeNode by allowing the enforcement of uniqueness constraints based on properties of its payload item (entity). |
| IdentityErrorExtensions | Extension methods for the IdentityError enumeration. |
| Adjacency | Relationship between two entities in a tree. |
| ErrorCheckOptions | Represents a list of options for error checking in a tree. |
| IdentityError | Represents a list of potential errors within the children of a tree node. |