Foundation
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Note on War Factories and outlines: On War Factories, the game uses FoundationOutline.10 as the primary exit destination for newly spawned units, using the eight adjacent cells as alternative destinations. These cells basically form what the game sees as the factory's "bib", regardless of graphics.
You are seeing this message because you have no FoundationOutline.10 defined - if you are not making a foundation for a War Factory, this note can be ignored.
You can set FoundationOutline.10 manually by shift-clicking anywhere on the canvas.