ENGINEERING ANSWER
The fabrication package should describe all copper, mask, legend, outline and drilling operations consistently. Material designation belongs in the drawing and order notes; it cannot be inferred reliably from the copper artwork.
What to decide before release
Inspect the exported package in an independent viewer. Check scale, units, origin, plated versus non-plated holes and controlled-depth operations. If using ODB++ or IPC-2581, agree the accepted format and revision with the supplier.
Checks to put in your design brief
- Include an unambiguous outline
- Separate plated and non-plated drilling
- Match file revision to the drawing
Important distinction
A correct CAD project can still produce an incorrect export. Review the files that will actually be manufactured.
Sources & basis
Material facts follow the cited source. Design checks are preliminary guidance, not supplier process instructions.