Shapes
The figures a diagram on the stage is drawn with (stage-shape): what they mean is the page's — a process, a workflow, a plan —, how they look is said once, on the tokens of the design system. Each one fills the element the stage gives it.
The box
A block of the design system with its edge drawn: what it is in its corner (block--mark), its words in the middle, three lines at most. Heavier (stage-shape--thick) for one that holds more than itself.
The circle
Where something starts, waits or ends: a glyph in it, its words under it. Its edge heavier (stage-shape--thick) or doubled (stage-shape--double), in a tone (stage-shape--tone-success, -warning, -error, -info).
The diamond
Where the way forks: the square turned, its glyph upright, its words under it; the same edges and tones as the circle.