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From SofTutor for MicroStation 3D - Creating a Slab
Topics & Keywords covered in this video are:

Placing A Slab Create Tools 3D Main Solid Surface XYZ
Placing A Solid Slab On The Screen Z Axis Create 3D Main Surface XY Ortho
Placing A Solid Slab On The Drawing Z Axis Create Tools 3D Main Surface XY Ortho