A currency symbol was used for the ruble between the 16th century and the 18th century. The symbol consisted of the Russian letters "Р" (rotated by 90° counter-clockwise) and "У" (written on top of it). The symbol was placed over the amount number it belonged to. This symbol, however, fell into disuse during the 19th century and onward.
In July 2007, the Central Bank of Russia announced that it would decide on a symbol for the ruble and would test 13 symbols. This included the symbol РР (the initials of России Рубль "Russian ruble"), which has received preliminary approval from the Central Bank. However, one more symbol, a Р with a horizontal stroke below the top similar to the Philippine peso sign, was proposed unofficially. Proponents of the new sign claim that it is simple, recognizable and similar to other currency signs. This symbol is also similar to the Armenian letter ք.
The winning symbol, RUB, is now the official ruble sign. As of 2013, it does not yet have a Unicode code point assigned, but work is proceeding to put it through the standardization process for code point assignment.