Can ETNs be sold short?

Can someone please clarify for me, are Exchange Traded Notes (ETNs) eligible for short selling? I've heard mixed opinions about the possibility of short selling ETNs and I'm hoping to get a definitive answer. I understand that the rules and regulations can vary depending on the specific ETN and the brokerage firm, but is there a general rule of thumb or a common practice when it comes to shorting ETNs? Additionally, if short selling ETNs is allowed, are there any specific risks or considerations that investors should be aware of? I'd appreciate any insights or guidance on this matter.