The discussion centers on the evaluation of a non-symmetric error function e(x,y) used to compare two positions and orientations of a drill, represented as elements of SE(3). The suitability of this function depends on the intended application, particularly whether it effectively captures the nuances of error in practical scenarios. While norms and symmetry can simplify proofs, they are not strictly necessary for demonstrating that the error is bounded. The asymmetry in the function can be justified, as certain errors may have significantly different implications, such as "drill too low" versus "drill too high." Ultimately, the effectiveness of the error measure hinges on its alignment with the specific context of its use.