Where can I find the numerical values of characters with the Hexadecimal Digit (Hex_Digit) property?
The Unicode Standard provides the Hex_Digit property, which specifies which characters are hexadecimal digits: 0-9, A-F, a-f, and their fullwidth equivalents. (The ASCII_Hex_Digit property specifies the intersection of the Hex_Digit property and the Basic Latin block.) There is no table in the UCD mapping the hexadecimal digit characters to their values, analogous to the Numeric_Value property. The table linked here removes this real, if trivial, gap.