Clean coal: oximoron or solution?

Clean coal; an oximoron if I ever heard one.  After the presidential debate last week, I was more confused than ever about “clean coal”.  What the heck is it?  Both candidates are in favor of it, but neither defined what it is.  I did a little research and from what I could tell, there is no clear cut description.  The one common thread was that it is cleaner than traditional coal burning methods.  There appears to be several methods of reducing carbon emissions and any of them fall under this category.  The clean coal plan lacks any reduction in mining impact on the environment, doesn’t improve safety for the workers and is not a sustainable energy source.