That's called unsecured funds and they are not allowed.

The promissory note can be secured or unsecured.

Is this a real estate loan, or is it an unsecured note? 

I am a lender on Prosper.com and it is legitimate and there are small real estate loans but they are unsecured.

Re the DTI or any other metric lenders typically use.For instance:-- Loan applicant A has an unused unsecured line of credit for (example) $10,000.-- Loan applicant B has an unsecured line of credit also for $10,000, but owes $10,000 on it.Applicant B seems obvious, but what about applicant A (???)

We often notice that people have not secured their locks properly or have accidentally taken their lock with them and the unit is unsecured.

(A recorded trustee's deed (or similar alternative) confirming the amount paid by the grantee to trustee may be substituted for a settlement statement if a settlement statement was not provided to the purchaser at time of sale.)The preliminary title search or report must confirm that there are no existing liens on the subject property.The sources of funds for the purchase transaction are documented (such as bank statements, personal loan documents, or a HELOC on another property).If the source of funds used to acquire the property was an unsecured loan or a loan secured by an asset other than the subject property (such as a HELOC secured by another property), the settlement statement for the refinance transaction must reflect that all cash-out proceeds be used to pay off or pay down, as applicable, the loan used to purchase the property.

I'd feel comfortable repeating that same loan on a similar deal, but I need something in my back pocket if someone comes to me with a long-term hold... or wanting to do an unsecured deal... or needing funds for a down payment... or they offer a share of profits... etc. 

If the source of funds used to acquire the property was an unsecured loan or a loan secured by an asset other than the subject property (such as a HELOC secured by another property), the HUD-1 for the refinance transaction must reflect that all cashout proceeds be used to pay off or pay down, as applicable, the loan used to purchase the property.

The local hard money lender I am with structures my investment as a loan to their lending entity (unsecured), but then has an underlying property where my source of funds went to that serve as collateral for the loan if the hard money lending company doesn't pay me.