What is an underlying 2024 producers certificate?

Hello- a customer in Mexico is asking for a underlying 2024 producer’s certificate. we have never provided such document or have i ever heard of such. Could anyone assist in clarifying what this document entails or even is. Was thinking Is this a certificate signed by an inspector onsite for exporting?
Thank you all for your help

Yeah, they really didn't ask for the right way - An underlaying producers certificate can come from the FDA, most do.

 

There are a variety of them, full details can be found here:

https://www.fda.gov/...rt-certificates