code: private static final boolean isDigit(char c) {
          int n = c;
          return n >= 0x0030 && n <= 0x0039 || n >= 0x0660 && n <= 0x0669 || n >= 0x06F0 && n <= 0x06F9 || n >= 0x0966 && n <= 0x096F || n >= 0x09E6 && n <= 0x09EF || n >= 0x0A66 && n <= 0x0A6F || n >= 0x0AE6 && n <= 0x0AEF || n >= 0x0B66 && n <= 0x0B6F || n >= 0x0BE7 && n <= 0x0BEF || n >= 0x0C66 && n <= 0x0C6F || n >= 0x0CE6 && n <= 0x0CEF || n >= 0x0D66 && n <= 0x0D6F || n >= 0x0E50 && n <= 0x0E59 || n >= 0x0ED0 && n <= 0x0ED9 || n >= 0x0F20 && n <= 0x0F29;
      }
docs: Determines if the specified character matches the <em>Digit</em> production.
  See: <a href="http://www.w3.org/TR/REC-xml#NT-Digit">Definition of Digit</a>.
  
  @param c the character to check.
  @return <code>true</code> if the character matches the production, or <code>false</code> if
  it does not.