What Does User Operation Prohibition (UOP) Mean?
User operation prohibition (UOP) is a feature that prohibits the user from performing certain functions during certain parts of a DVD or Blu-ray disc. Most commonly, this is used to prevent one from skipping legal disclaimers or advertisements. The DVD/Blu-ray player displays an error message or symbol when a prohibited action is attempted.
Techopedia Explains User Operation Prohibition (UOP)
User operation prohibition finds its utility in FBI warnings against piracy or copyright control and unskippable commercials. Many DVD players override the UOP command and play the movie immediately if stop-stop-play is pressed. In most cases, removing UOP does not guarantee free navigation throughout the restricted part, because sometimes the sections covered by UOP do not have the controls for skipping to the main menu or other parts of DVD built in. This has become more common in more recent DVDs and DVD players in order to maintain the UOP command and control.