1. Component Dimensions (for the IPC Calculators)
2. Mfr. Recommended Pattern (for the FP Designer unique parts)

There are several hundred rules in Preferences to allow every user the opportunity to create the footprint that meets your personal corporate guidelines. Pad Shapes, Drafting Line Widths, Clearances, Solder Joint Goals, Masks, Origins, Rotations and on and on are in the Preferences file.

Most PCB Fabrication shops now use Ink Jet Printers to apply the silkscreen and it's very accurate.

Buy using corn hatch marks and thin lines saves Ink Cartridges.

But it's a User Preference. I talk to many companies and they are using the IPC default to achieve the highest packing density in their part placement.

You can set the silkscreen line width and clearance value to whatever you want.

PCB Libraries doesn't sell CAD libraries, we sell FPX files with component dimensions.

Every User defines their own pad shapes, rules, drafting line widths, zero rotations (pin 1 location), solder mask swell and many more user settings.

The reason why IPC uses 0.12 mm (5 mil) is because the "Nominal" courtyard excess in 0.25 mm (10 mil) and if the line width and clearance are 0.12 mm the silkscreen doesn't push the courtyard excess out.

If your silkscreen outline line width and spacing in 0.20 mm (8 mils) then your placement courtyard will be pushed out 0.40 mm (16 mils).

The silkscreen should stay inside the placement courtyard excess.

Do you think we should add a new User Preference for "Allow Silkscreen Outside Courtyard"? Then the placement courtyard rule would override the Silkscreen Rule.