The multiple-choice purpose is typically selected as “Line for future useâ€.
I would try to get rid of that option. I would make the choices line up with HMDA unless someone is using those options for something. We used to have several dropdown options, and it was a pain. We asked, and nobody else used/cared about that field. A system fix with a little LO training made life a lot easier on the back-end.
Besides that, I agree with everyone else. Document what they say, even if it's not for sure. If you have something in the file that says purchase, then you're done, if not, move on down the purpose waterfall until you hit Other.