I presume the ..OTP end of that acronym refers to 'One-Time-Password' but I'm not sure what the first T is. Not helped by the fact that, for anyone of a certain

I presume the ..OTP end of that acronym refers to 'One-Time-Password' but I'm not sure what the first T is. Not helped by the fact that, for anyone of a certain age who grew up in the UK, the initials TOTP can only ever stand for 'Top Of The Pops' https://en.m.wikipedia.org/wiki/Top_of_the_Pops https://en.m.wikipedia.org/wiki/Top_of_the_Pops