A new function has been added to the latest OCAD 2018 Service Update: Vectorize automatically cliff features.
With OCAD, you can now automatically convert cliff features from the Slope Gradient calculation into vector symbols.
Please find more information in our Wiki.
To use this function, you need the latest OCAD 2018 Service Update, which can be downloaded from the Help -> OCAD Service Update function in the OCAD program.