Am 19.08.2016 um 16:46 schrieb Allin Cottrell:
 On Fri, 19 Aug 2016, Sven Schreiber wrote: 
 One other consideration: at present, loading a new dataset from file
 (via "open" or the GUI equivalent) clears out the entire existing
 workspace, unless --preserve is used. The current handling of "nulldata"
 is consistent with that behaviour.
 So actually I'm not sure about this ;-)
 
Yes probably the whole business of "open", "clear",
"nulldata" must be 
thought through together.
-sven