The karbovanets or karbovanet (карбованець, plural: карбованці, karbovantsi for 2–4, or карбованців, karbovantsiv for 5 or more), also known as kupon (купон, plural: купони, kupony) or coupon, has been a distinct unit of currency in Ukraine during three separate periods of the 20th century. It is also a predecessor currency of today's Ukrainian hryvnia. The karbovanets was subdivided into one hundred kopiykas, but no denominations in kopiykas have ever been issued. In the ISO 4217 standard, the official name is spelled as karbovanet, while English version of the National Bank of Ukraine's website refers to it as karbovanets. In March 1917 in Kyiv, some political parties formed the Central Rada which proclaimed on 20 November 1917, the foundation of the Ukrainian People's Republic. And by just December 19 of the same year, a temporary law about the issue of state banknotes by the UPR was adopted. According to this law: "Banknotes must be issued in karbovanets" (Карбованець). Each karbovanets contains 17.424 parts of pure gold and is divided into two hryvnias Гривня or 200 shahs (Шаг). The etymology of the name "karbovanets" is debatable: by one supposition it originated in Ukraine from the ancient primitive way to carve (karbuvaty, Карбувати) numbers of calculations on a rod, and by another supposition – from the carving (incision) on a rim of a metal rouble. On 5 January 1918, the first Ukrainian banknote with a value of 100 karbovanets was issued. There is an interesting detail: the trident depicted on the banknote was proclaimed as a National Emblem of the UPR only on 25 February 1918. On all issued banknotes was stated only one series – "AД" and only one number – 185. Combined with the use of ordinary paper (without watermarks) for printing of this banknote, this led to the appearance of a great number of counterfeit bank-notes in circulation. On 20 September 1918, the Central Rada proclaimed the issue of banknotes of the State Treasure in denominations of 5, 10, 25, and 50 karbovanets, to be valid until 1 March 1924.