Protonic defects has been used several times in discussions of protons existance in high temperature proton conducting metal oxides. When I read some articles, I got difficulty to understand what really the proton defects stand for either is for the excess or absence of protons. which one is proper? More challengingly, is when hydrogen defects used instead of proton defects. i.e. Sentence substracted from one article: The structural, dynamical, and electronic properties of ionic defects in ........created by the addition or removal of a proton have been studied using the method of ab initio molecular dynamics. These protonic defects correspond..............