This command sets the text for the two title lines. Because KUPLOT treats the ',' as a parameter separator it can not be used within the label <string>. The command allows to build a label from a format text and variables/numbers. It is the same mechanism as described in -> filenames.
Examples:
tit1 Powder data ZrO2 : 'Powder data ZrO2' tit1 "Run #%d / Sample #%d",i[1],i[2] : 'Run #1 / Sample #5' (for i[1]=1 & i[2]=5)