Mikulovská wine grown in Mikulovská than any other Moravian region. The most planted red varieties are Saint Laurent ("Svatovavrinecké", 310 ha), Blaufränkisch ("Frankovka", 248 ha), Zweigelt ("Zweigeltrebe", 181 ha), and Pinot noir ("Rulandské modré", 172 ha). Plantings of Blauer Portugieser ("Modrý Portugal", 92 ha) has decreased rapidly, while Cabernet Sauvignon (89 ha) has increased. The Czech Wine Classification System, set in the Viticulture Act of 2004, is based on the sugar content of the grapes at harvest. Sugar content is measured using the Normalizovaný moštomer (°NM) scale, a measure of how many kilograms of sugar are in 100 litres of must. 1
Brix prism; the result is observed through an eyepiece. The critical angle (the angle beyond which light is totally reflected back into the sample) is a function of the refractive index and the operator detects this critical angle by noting where a dark-bright boundary falls on an engraved scale. The scale can be calibrated in Brix or refractive index. Often the prism mount contains a thermometer which can be used to correct to 20 °C in situations where measurement cannot be made at exactly that temperature. These instruments are available in bench and handheld versions. Digital refractometers also find the critical