PUT DATA: It causes all the variables known to the program at the point of the PUT statement to be outputed in the form of assignment statements. Since this is at the expense of considerable programming overhead, it should be used only for debugging. e.g.
ON ERROR SYSTEM ;
who can tell me what is the 'PUT DATA' used for in this program?
There won't be much overhead as this code won't be executed unless there is a system error which causes the program to abend. In that case its intended to display all the variables, so that a proper analysis can be done.