Figure 22 in the Parent section of the Blender Manual is Incorrect. It does not show what was described in the manual:
To check weather a particular bone in an armature is a Deforming Bone simply switch to Pose Mode or Edit Mode on the armature and select the bone you are interested in by RMB it. Once the bone of interest is selected navigate to [Properties Editor > Bone Context > Deform Panel] and check if the Deform tickable option is ticked or not. If it is the selected bone is a Deforming Bone, otherwise it is a Control Bone. See figure 22.