Dear IDL user, I have created a list like a=list(arrA, arrB, arrC, arr...) and each of the arrays contain parameters like arrA=['para1', 'para2', 'para3', ....] . Using an outer FOR loop for the elements in the list return a string of the elements. With an inner loop I like to step over the different arrays to retrieve values for the parameters. Any suggestions on how to loop over the different elements inside the arrays are appreciated - or is there in general a better way to get it run? Regards,