These are invariably matured in wood, with a small proportion also fermented in wooden casks, and have a very long cellaring potential. As botrytis is undesirable in these wines, the grapes must come from high-elevation vineyards (about 250 m/820 ft) designed specifically for this purpose. These are mostly single-vineyard wines and expensive wines.
ยฉ Jancis Robinson and Oxford University Press 1994, 1999, 2006, 2015