Each script has a main interval setting. When a command has an optional interval parameter and it isn't set, this interval will be used. A good example is the historical price data commands like ClosePrices() or HighPrices(). The default data returned will be on the main interval if not specified.
When a script needs data in multiple intervals, we can specify the interval in minutes or using a more dynamic approach with the InputInterval(). This will create an interval drop-down that allows us to select any interval we want.