Interesting idea and one that we've discussed in depth. Just getting the authors to check the correct boxes can be tough. Yet I agree there could be a few more from which to select.

Author warnings at the begining of the story can very valuable. They can say what they want, put in more than the codes and those who may not like any particular type of story have been given another chance to change their mind.

For authors reading, I appreciate warnings like:

character death
violent death
brutal treatment of slaves
graphic descriptions of someone tortured to death
graphic descriptions of brutal rape

These types of warnings can assist the reader make a better decision.

Here's an example from Jay Merson's The Messenger of Pain
http://www.bdsmlibrary.com/stories/a...?authorid=1490

At the bottom of the description is
WARNING: Contains extremely hard and nasty scenes.

A great warning and very true for his tale.