Once I extract the lines from a file into a list, I want to check if a line is empty or not before processing it. How do I do that in PAD? Also, is there a way to define the NULL value in PAD?

Once I extract the lines from a file into a list, I want to check if a line is empty or not before processing it. How do I do that in PAD? Also, is there a way to define the NULL value in PAD?
For each through the list and use If %CurrentItem% Is empty (select operator in the dropdown)