meaning - "put down" ≠ make a down payment?

A Peace Corps volunteer started a credit union requiring people receiving a new home to put down community references in lieu of collateral. These references were friends, family members, or neighbors who could vouch that the applicants would pay the loan. The decision to create these arrangement was based on microfinance – the idea that people would be more likely to default on their own possessions than to compromise their reputation in the community and let their community down […]"

I'm quite confused as to the meaning of "put down" on this sentence. I thought it could mean "down payment", but you can't put down a person…

And collateral is something the person owns that serves as a guarantee, but if it's part of the a down payment, it's no longer a guarantee.

So I don't think put down really means make a down payment. Could somebody please explain how this system works and what "put down" means in this sentence?

Answer

Put down does have a meaning write down which could easily extend to nominate or register in this case. See definition 29 at Dictionary.com:

29. put down
a. to write down; register; record.
b. to enter in a list, as of subscribers or contributors: Put me down for a $10 donation.

What you don't want is another standard sense — which could be applied to humans, I suppose:

k. to put (an animal) to death; put away.