Double back

[Johnman]

At US airports they use the term Double back in their taxi clearances.Is this a standard term.(example :-double back on B and join txy...etc).

[Gonzo]

I've never heard of that in the UK, on the part of ATC. I have heard it said as part of a readback by an American flight crew though.

[chevvron]

Does that entail a 180 or a 360?