in tradestation, click view -> chart options -> symbol. uncheck the "show empty" periods you will see there. in Globalserver the times can be entered to start/stop for each period. if break was from 12 to 1 you would have it like - (open)monday 0800 (close)monday 1200. then next line would be (open)monday 1300 (close)monday 1500 ... the "show empty" periods setting wouldnt be needed w/ correct gs setup.