Constant std_tools::dependencies::strs_tools::string::number::protected::format::INTERNAL_DIGIT_SEPARATOR

pub const INTERNAL_DIGIT_SEPARATOR: u128 = INTEGER_INTERNAL_DIGIT_SEPARATOR | FRACTION_INTERNAL_DIGIT_SEPARATOR |
    EXPONENT_INTERNAL_DIGIT_SEPARATOR; // 30_064_771_072u128

Digit separators are allowed between digits.