I'm a software developer in my company and I have to write a report about a task I've done this past year. I'm doing this for the sake of maintenance and transparency in the work. In a nutshell, the task was about improving a functionality created by a coworker.
I have to explain in the report why I did certain things and one of them was an improvement of the code written by my predecessor. The real reason is that the code wasn't perfect and I knew I could improve it so it could be easier to understand and to maintain. The thing is we have different professional background and specialities so I can't and won't reasonably blame it about this.
Therefore my question is : How can I explain him what I did without suggesting that he did a bad work ?
I can't write "the quality of the code was bad", or anything that suggest that I'm better than him, that's not what I think, who I am but I still have to explain my decisions.