What is a bitcoin ETF symbol?

Could you please elaborate on the concept of a Bitcoin ETF symbol? I'm curious to understand what it represents and how it functions within the cryptocurrency and financial landscape. Is it a unique identifier for a Bitcoin-related Exchange Traded Fund? If so, what role does this symbol play in enabling investors to gain exposure to Bitcoin without directly purchasing the cryptocurrency? Additionally, are there any specific requirements or regulations that govern the use of Bitcoin ETF symbols? Thank you for your clarification.