What is CTX remittance advice?

Excuse me, could you elaborate on what CTX remittance advice entails? I've heard the term mentioned in the context of cryptocurrency transactions but I'm still unclear about its specific purpose and functionality. Is it a document that accompanies a transaction to provide details? Or is it a type of verification system? Additionally, how does it fit into the broader realm of financial transactions and specifically, within the cryptocurrency ecosystem? I'd appreciate any clarity you could provide on this matter.