In case you base your condition on the current date, you can use the TODAY() function in the logical_test argument of your IF formula. For example: Naturally, the Excel IF function can understand more complex logical tests, as demonstrated in the next example.
A sink mark is a local surface depression or void that typically occurs in moldings with thicker sections. They are also common in locations above ribs, bosses, or internal fillets. As the plastic cools at different rates in the mold, the surface hardens but leaves the thicker areas in the center still molten.
A proof mark is a mark specific to the manufacturer, importer, or testing facility that is performing the test. It generally takes the form of a stamp that makes an impression in the metal.