An out of date discussion is an archived Panopticon thread which describes a state of this wiki that simply doesn't exist any more. Perhaps it talks about features that are no longer present, or discusses changes to a skin that's no longer available from Wikia, or maybe it's about plans that are simply no longer relevant.
Note that sometimes the border between an "out of date" thread and a "policy changer" or "design changer" can sometimes be very narrow. Generally, if it can be established with certainty that the thread proposal was adopted, even if it is now no longer in use, it's better to categorise it as a policy changer or a design changer. That way, people trying to trace the origins of an idea can stick in one category. If, however, the proposal went nowhere, or the thread uses a template call to a still-active template which has changed so much it no longer illustrates the points being made, it's probably best described as an out-of-date thread.
One of the most obvious signals of an "out of date" thread is any thread which refers to features in the Monobook or Monaco skins. If the feature is no longer available in the Wikia/Oasis skin, it's out of date.
The following 116 pages are in this category, out of 116 total.