There was a lengthy discussion about this on FB SpaceX group. TEL is actually incorrect. Transporter Erector (TE) is correct. Because SpaceX uses their TE as a horizontal transporter then actually launches from it (sort of), a lot of people incorrectly was referring to it as a TEL (as in Transporter Erector Launcher). Technically the erector pulls away from the launch vehicle just before launch which is why TEL is incorrect. Hopefully I explained it well enough.