An internal counter determines the pointer to be returned by a series() call. Therefore, series can only be created in the run function or in a function that is called from the run function; and they must be always created in the same order. Thus series calls must not depend on if or any other condition that can change from bar to bar (see example below). These requirements also apply to all functions that internally create series, such as some indicator or signal processing functions. Zorro detects wrong series calls and will display an error message in this case.