I have a reason to believe that my co-worker is replacing my initials with his on drawings that I created (completely). We are the only two that work on CAD. All these years I've been a designer/draftsman, I've never encountered this and am wondering, is there any kind of ethics being broken here? What is the importance other than reference (and pride of work done and responsibility) for our initials? Any and all input would be appreciated. Thanks