What is tau levels?

Could you please clarify what you mean by "tau levels"? Is this referring to a specific metric or indicator used in the world of cryptocurrency or finance? If so, could you provide some context as to where this term might be used and what it represents? Alternatively, is this a term from a different field that you're inquiring about, and you're wondering how it might relate to cryptocurrency or finance? Without more information, it's difficult to give a precise answer to your question.