Earthing systems new approach

Hi all earthing systems and understanding them is something we've all had to do in our working lives. One thing that I think makes it harder to get our heads around different systems and the way they are described is the odd way the letter T is used to mean earth why T? Is it as someone suggested from some word or phrase in Latin? I really don't know for sure what I wonder is tho can the IET or whoever is best placed to do it come up with a more sensible lettering system please? The obvious ones are E or G  the rest of the letters could be changed too if needed. The whole aim is I have is to make it all more descriptive so that it's easier to keep in our heads what do you think?  Hope someone replys X Kelly