> sometimes the 'why' is about the code that wasn't written, so it can't possibly be in the code that was. I have often had to write extensive comments related

> sometimes the 'why' is about the code that wasn't written, so it can't possibly be in the code that was. I have often had to write extensive comments related to this to prevent well meaning coders who are not expert in the domain from replacing the apparently bad or low performance code with an obvious but wrong 'improvement'.