There is no definition in Reg. Z for "investment properties". The only definition i know of in Reg. C for them is for owner occupancy with the direction to code anything that isn't a primary or secondary residence as "investment". I would tread lightly with the idea that anytime an LO throws out the word "investment" it must automatically be for business purpose. Lots of threads out there that discuss this, but again, Reg. Z is pretty specific about automatic business purpose exemptions, for non-owner occupied rent homes. There are no exemptions in Reg. Z whatsoever for "investment properties". There are consumer investment properties (i get a loan to buy out a sibling's interest in a family-owned property) and there are business purpose investment properties (a builder gets a loan to buy and flip a home).
I don't know if this helps with your software questions.
I'm fixin' to fix that.