The File to Attach window is shown when you add or edit an external file attachment for an E-Mail Task.
Enter or browse to select the name of the file you want to attach. This field can contain variables and functions that are replaced at runtime. More... Click the {} button
to display the text editor, which helps you insert variables and functions into the text. When you hover your mouse pointer over the field for a second, a preview of the "expanded" text will be displayed so you can confirm your variables and functions are working correctly.