If you hold down the Option key and click on the Clear button (its title will change) you can customize what fields are cleared. Many people don't want all fields cleared when they click the Clear button.
At any rate, clearing the append (+) check boxes is not something that is customizable and they are never cleared. Clearing the append check boxes can completely change one's workflow. When applying the IPTC Stationery Pad it can be disastrous. It is for this reason that we do not clear them.
-Kirk
I don't get it myself, but I believe you when you say that clearing the append checkboxes can be disastrous. However, it's obviously only disastrous for SOME people. For others, leaving it checked is a problem too. If the Clear button did not have the option to be customized, then of course you would have to make a call one way or the other whether or not to clear the append boxes. That I could understand.
The thing I don't understand is that even with the ability to customize the Clear button, you still can't clear everything. PM is set up by default to never clear the append boxes, so those folks are well looked after. For the rest of the users who would prefer to clear everything, can't we at least have the option?