A grammatical marker, descended from early scribal practice. In German, and often in East European languages, the comma is used as an open quote. Throughout Europe, it is also used as a decimal point, where most North Americans expect a period. In North American usage, the comma separates thousands, while a space is preferred in Europe. Thus 10,000,000 = 10 000 000, but a number such as 10,001 is typographically ambiguous. In Europe it means ten and one one-thousandth; in North America, ten thousand and one.