Check units, rotation and board layers

A numeric placement value can still describe the wrong physical position. Choose the coordinate units explicitly, then distinguish syntax checks from geometric and assembly review. The checker has no board outline, footprint model or pin-1 evidence.

One unit setting for the entire CPL

Factory-neutral mode accepts millimeters, inches or mils. One mil is 0.001 inch. The following values describe the same distance:

Bare numbers use your selected units. An optional mm, in or mil suffix must agree with that selection. A value of 25mm with inches selected is a blocker. Mixed-unit files need correction before checking; the tool does not silently convert individual cells or rewrite the source.

Signed decimal numbers and scientific notation are supported. Decimal commas are not: 12,4 is two CSV fields unless quoted, and a quoted decimal-comma coordinate is still unsupported. Export decimal points. NaN, Infinity, blank values, unit words such as inches and non-finite conversions are blockers. A local sanity bound rejects absolute converted coordinates greater than 1,000,000 mm; it is a parser limit, not a factory capability.

Rotation validity is not orientation correctness

Designator,Mid X,Mid Y,Rotation,Layer
U1,22.5,20,90,Top
R1,12.4,8.2,360,Bottom

The numeric value 90 passes the rotation syntax check. It does not establish whether U1's pin 1 will face the correct direction. A value of 360 generates a warning because it lies outside the tool's ordinary [0, 360) review interval. Negative values do too. The tool never normalizes or rotates a component automatically.

JLCPCB specifies millimeter centroid coordinates, Top/Bottom layers and degree rotation with positive angles counterclockwise. Its description establishes a file convention, not evidence that your footprint's zero-angle orientation matches the factory model. Source: JLCPCB pick-and-place guide.

Layer labels need a known interpretation

Factory-neutral mode recognizes top/bottom, front/back and F.Cu/B.Cu, ignoring case. It does not move or mirror coordinates. The JLCPCB basic profile accepts only Top/Bottom labels, again ignoring case. Unknown labels such as inner or component-side are blockers rather than guesses.

Check the exported origin, centroid choice, bottom-side coordinate convention and polarity against the CAD assembly drawing and receiving factory preview. Those questions require evidence absent from these two CSVs. A clean report cannot certify them. Review the basic-profile limits before interpreting a manufacturer-specific result.