Excluding an item from a category

Hi, is there away to display all items in a category and excluding just one item from the category. For instance, I'd like to display {.... catid="100" notDisplayID="3"} Is there away to not display id="3" since it is in category 20. The only way I thought of doing it is to display each id separately, however this would take a long time, since items are always added later, which means that I would have to modify the modules all the time. However, excluding an 'id' from a category would work perfectly. Any idea? Thanks

Thanks for getting back to me.
I understand you can change the category of that item but I don't want to do that because I will be using that specific item in a different place and excluding a different item. For instance, in one place, I'd like to use {.... catid = "100" notDisplayID = "3"} in another place, I'd use {.... catid = "100" notDisplayID = "7"} and so on. Is there away to easily modify a portion of the code to be able to have this functionality. Thanks