A specific type of
item in the
Final Fantasy series* where the item may not be
used or
equipped as par a normal item, nor
discarded. The item may only be used to advance the story, but still resides in
inventory. These items usually reside in a special menu, but have been known to live in the general inventory in some of the series' titles (
Final Fantasy IV comes to mind).
Often, just owning the item will trigger the events to further the story when you talk to the right person. However, sometimes you must actually use them in the proper location. This action is usually prompted by a item menu coming up when you talk to something.
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* As well as other games, I'm sure.