It's not that it's between TE and MET but just that the pipes are connected to the CPCs.I am not sure if it's worth showing the connection between true earth and the MET.
What should I call it?Also true earth is a bit of a misnomer, as there's only local earth which may vary significantly from other local earths. But I'm not sure how you'd indicate that,
I don't want to get too complicated.maybe a brown resistor symbol between the supplied earth and the ecps?
It's just for showing DIYers when they ask "I have a pipe, does it need bonding?".