#679 `<surfaceGrp>` has attributes it shouldn't

[Martin Holmes]

Arising out of this ticket:

http://sourceforge.net/p/tei/feature-requests/488/

and out of the consequent discussion at the FTF in Oxford in 2014, it seems clear that <surfaceGrp> should not be a member of att.coordinated. It's simply a grouping element for <surface> elements. I think this is a corrigible error.

[Lou Burnard]

I agree, and have taken the liberty of correcting it at rev 13014