naturally without any artificial heat source. Vintage or Frasqueira – This style must be aged at least 19 years in a cask and one year in bottle, therefore cannot be sold until it is at least 20 years of age. The word vintage does not appear on bottles of vintage Madeira because, in Portugal, the word "Vintage" is a trademark belonging to the Port traders. A wine labeled as Finest has been aged for at least three years. This style is usually reserved for cooking. The terms pale, dark, full, and rich can also be included to describe the wine's colour. Madeira produced from Negra Mole grapes used to be legally restricted to use generic terms on the label to indicate the level of sweetness as seco (dry), meio seco (medium dry), meio doce (medium sweet) and doce (sweet). However, in 2015 the Madeira Wine Institute announced that producers may officially recognise Tinta Negra on their front labels and that all "expressions" must state their bottling date. Wines listed with Solera were made in a style similar to sherry, with a fractional blending of wines from different vintages in a solera system. The Solera method of blending is most widely practiced in the sherry production of Spain. However, the rules for Madeira soleras are different. When it comes to sherry, as wine is used for bottling, new wine is added to the barrels of older wine and this continuous addition of young wine to old would result in very little wine being from the original vintage. With Madeira, approximately 50% of a bottle would likely be from the stated year because they are only allowed to add up to 10%, not more than 10 times. Another interesting peculiarity of old solera Madeiras is that they were initially developed as a result of trying to extend the stocks of vintages when the vines had stopped being productive due to Phylloxera. Therefore, as there was no younger wine to add to the vintage, it was usually older wines that were added. In recent years, vintage Madeiras have been commanding higher prices than soleras, but, from 1966 (when Michael Broadbent started wine auctions at Christie's), until about the end of the 20th century, solera Madeiras always fetched a premium at auction over the vintage ones. Rainwater A style called "Rainwater" is one of the largest-selling styles of Madeira in the United States. This