https://grafioschtrader.github.io/gt-user-manual/en/basedata/instrumentbased/stockexchange/tradingcalendarruleset/index.htmlA rule set describes the public holidays of one or more stock exchanges as rules. From these rules GT calculates the closed days of the trading calendar for each year. Unlike the index for trading calendar, a rule set also works for future years for which no price data exists yet, and it needs no index traded on the exchange. A stock exchange uses either an index or a rule set, never both at the same time.Hugoen