Added 'ceiling' and 'floor' enumeration selections to 'interpolate' attribute of <independentVarPts> and <independentVarRef> elements at the suggestion of Geoff Brian, Giovanni Cignoni, Randy Brumbaugh, and Daniel M. Newman.

Added five uncertainty examples.

Cleaned up all FIXME and BUG notes.

Corrected and expanded the labels on the DAVE-ML excerpt figure.