This isn't utilized as much as it used to be back when we were converting, but sometimes we need to see what that historical ICD-9 code is. So if I want to use this conversion tool, I could go in and say, okay, my ICD-10 code was, let's use hypertension again, I10.

It's gonna give me what my ICD-9 equivalent was. So what is being mapped from one to the other?