small update to allow creation of empty unlimited datasets

da/tools/io4.py

@@ -358,7 +358,8 @@ class CT_CDF(netCDF4.Dataset):
                 if k not in ['name','dims','values','_FillValue','count']: 
                     var.setncattr(k,v)
 
-            if nsets > 1 or self.has_unlimlen(datadict['dims']) == True:
+            #if nsets > 1 or self.has_unlimlen(datadict['dims']) == True:
+            if nsets > 1 or (nsets > 0 and self.has_unlimlen(datadict['dims']) ) == True:
                 ndims = var.ndim
 
                 datadict = ConvertCharDims(var,datadict)