"General Letter" included with cash offers?

[Michael Barnhart]

Hello BP! Has anyone been asked by their realtor that they need to submit a "General Letter" along with their cash offer stating that you have a private lender that will be funding the deal? I will have a Promissory Note signed to borrow the private money that will include all the details about the money and property as collateral but I'm just curious what needs to be included on this "General Letter." If someone has an example, that would be excellent as well! Thanks!