I think usage and the folk process has led to yearn meaning head off as
a couple on the (left) diagonal towards a new couple then do what the
caller says, usually either back off straight so that they are your new
neighbours or back off on the next diagonal to make the next couple your
new neighbours.
We have slices, double slices and half slices as well.
I think this is similar to the way that you have to be careful whether
you say half a ladies' chain, a ladies' chain, or a full ladies' chain
depending on the context.
Happy dancing,
John
John Sweeney, Dancer, England john(a)modernjive.com 01233 625 362
http://www.contrafusion.co.uk for Dancing in Kent