code: protected boolean validateMatch(String srcString, String substring, int matchStart, int matchEnd)
      {
          if ((matchStart == 0 || !Character.isAlphabetic(srcString.codePointAt(matchStart))) && //require something non-alphabetic chars around
                  (matchEnd == srcString.length() || !Character.isAlphabetic(srcString.codePointAt(matchEnd))))
          {
              final int num = Integer.parseInt(substring);
              return validateRange(num);
          }
          return false;
      }
docs: Validates the substring match -- checks the neighborhood and numeric range. This may be overriden
  for particular use cases.
  @param srcString the whole source string
  @param substring the matched substring
  @param matchStart start index of the substring in the whole string
  @param matchEnd end index of the substring in the whole string
  @return true when the match corresponds to the number range and other limitations