- char-set:digitconstant
In Unicode, a character is a digit if it has the general category Nd in the character attribute database. In Latin-1 and ASCII, the only such characters are 0123456789. In Unicode, there are other digit characters in other code blocks, such as Gujarati digits and Tibetan digits.
Some Unicode digits:
0660 ARABIC-INDIC DIGIT ZERO 0AE6 GUJARATI DIGIT ZERO 0F20 TIBETAN DIGIT ZERO