When you start the PartEditor, the GeometryTree replaces the KinematicsTree.
This is the symbol at the head of the GeometryTree  labelled 'ConstraintLoops'. 
Example: Geometry in ElementExplorer 
What is a ConstraintLoop? Each ConstraintLoop [labelled as 'Constraints'] lists the constraints that you have added to or between sketchelements. The Points are also in the Constraint Loop. Constraints that relate a set of sketchelements are listed in one ConstraintLoop. Constraints that relate a different set of sketchelements are in a different ConstraintLoop. If a Constraint relates the two different sets of sketchelements, the two ConstraintLoops combine into one ConstraintLoop that lists all of the Constraints. For example:
