You can use the LabelDirection macro command to control the orientation of the numbers along each axis. 0=horizontal, 1=45 degrees, 2=vertical.
These settings are ignored for polar plots, triangle plots, and 3D views of 3D or 4D data.
For polar plots, you can change the orientation of the radial labels to vertical with the PolarPlotStyle macro command.
The following example sets the X axis label direction to 45° for the currently active DPlot document:
Dummy=FNDplot_send_cmd("[LabelDirection(1,0)]")