class IQFeedSocket : Socket() {
    fun start() {
        connect(InetSocketAddress("localhost", 9100))
        val brBufferedReader = BufferedReader(InputStreamReader(this.inputStream))
        val brBufferedWriter = BufferedWriter(OutputStreamWriter(this.outputStream))

        // Initialize the protocol, this prepares us for commands to come and verifies that our socket is working as intended.
        brBufferedWriter.write("S,SET PROTOCOL,6.2\r\n")
        brBufferedWriter.flush()

        brBufferedWriter.write("HDX,AAPL,30\r\n")
        brBufferedWriter.flush()
        thread {
            var line: String
            while (brBufferedReader.readLine().also { line = it } != null) {
                println(line)
            }
            brBufferedReader.close()
            brBufferedWriter.close()
            close()
        }
    }
}

• If the expiration day is a single digit, it gets a leading zero, e.g. AAPL2309H175 if the expiration day was the 9th.


• Strike Prices do not get a leading zero, e.g. AAPL2325H50


• Call options are A-L in order by month, put options are M-X in order by month. AAPL2325H175 is a call option; the put option for the same strike price would be AAPL2325T175. Here's the list: https://help.tradestation.com/10_00/eng/tradestationhelp/symbology/month_codes_stock_index_options.htm


• Sometimes there will be an extra number in the option symbol, like FWOA22315I50. This typically happens when the underlying symbol splits; the extra digit represents some kind of change in the deliverable or price. https://infomemo.theocc.com/infomemo/search is a good source of information about this. Each symbol has a memo and a description of what the new option symbol means exactly. You can even look up FWOA (it's memo number 53034).