PDF (adobe.com)

Create nonprinting objects

You might want to create objects that appear onscreen, but will not be printed or appear in portable versions of the document.

You can also use layers to selectively hide or show elements in a document, and you can assign layers a non-printing status.
  1. Select the object or text frame that you don’t want to be printed.
  2. Open the Attributes panel (Window > Attributes).
  3. In the Attributes panel, select Nonprinting.