AddDeltaModeToPlot:

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   Add mode changes to a plot.
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   Form:
   AddDeltaModeToPlot( hAxis, oldMode, newMode, t, x )
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   ------
   Inputs
   ------
   hAxis       (1,1) Handle to axis
   oldMode     {:}   Old Modes
   newMode     {:}   New Modes
   t           (:,:) Time of mode transition
   x           (3,:) Location

   -------
   Outputs
   -------
   None

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