The Create by Viewline is used to create a section of a Drafting Palette object/view.
You create a View with the Drafting Palette, insert that view into Paper Space, and draw a line through this view. Then you use the Create by Viewline, select the view, select the line, pick which side of the viewline you want... and you now have the view that you want.
See Attached... maybe it will help.
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