The drawing plane is world XY, but break, join, rectangular array, the
stretch/window move, the spline preview wire and several doc comments
still used the stale "Y-up XZ" mapping (world Z = DXF Y). That made
those commands operate against a constant-elevation axis: arc/circle/
line/spline break and join picked the wrong points, rectangular array
stepped rows along the Z (elevation) axis, window-stretch tested the
wrong window bound, and the spline wire drew in the wrong plane.
Map every drawing-plane coordinate through .y (elevation on .z),
matching the entity builders, the inquiry commands and the central
transform. Stale Y-up comments updated to avoid future confusion.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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