Design-rule check (DRC)

Verify → Design rules… opens a per-layer table of limits: min width, min spacing (both in µm), min area (µm²) and grid (nm). Leave a cell blank to skip that check. One-click writer presets set the min-width floor on every layer at once — laser (1.5 µm), e-beam (200 nm), BEAM (500 nm), or soft litho / PDMS (20 µm, the low-cost soft-lithography foundry floor for microfluidic masters).

Press F7 (or Verify → Run design-rule check) to run. Then:

• Every SRef / ARef in the active cell is expanded first, so a spacing error between two instances of the same cell is caught — it only exists in the parent, and checking the un-expanded cell would report clean.
• The check runs in a background worker with a Cancel button, and is strictly read-only: it never touches your drawing or the undo stack.
• Violations appear as numbered markers on the canvas. Press F2 / Shift+F2 to step through them; the view zooms to each one with enough surrounding geometry to see what went wrong. Verify → Clear violations removes them.
• When violations cluster tightly, overlapping labels are automatically hidden so the rest stay legible — the marker you've stepped to with F2 always keeps its label, even in a dense cluster.
• Grid flags every boundary, box, and path vertex that isn't a multiple of the entered grid (nm) — the classic "on-grid" manufacturing check. Because instances are expanded first, a rotated or magnified instance is caught even when its cell is itself on-grid, and a grid-only rule set skips the heavy geometry merging entirely, so it stays fast on any layer.

Rules are remembered in your browser and apply to whatever document you open — they describe the process you intend to fabricate with, not the drawing. They are not written into the .gds.

What is checked: boundaries and boxes — and, by the grid rule alone, paths too. What is not: paths under the width/spacing/area rules (Glyph tells you when a checked layer contained paths those rules skipped, rather than implying a clean result), enclosure/overlap between layers, and connectivity. Very dense layers are slow — the check is exact, not sampled.