code: func isIA5String(b []byte) bool {
  	for len(b) > 0 {
  		r, size := utf8.DecodeRune(b)
  		if r < 0 || r > 127 {
  			return false
  		}
  		b = b[size:]
  	}
  	return true
  }
docs: // Range from: http://www.zytrax.com/tech/ia5.html