Metric or Inches?
For for people that use metric measurements instead of United States Customary Units (USCU) (inches, feet, yards) - (I just learned that term tonight!)
How are the quilting patterns written? What measurement system is used?
If written in USCU - do you mentally think -ah, 6 mm for a seam allowance instead of 1/4 inch.
6 mm is "almost a perfect scant 1/4 inch"
(1/4 inch is about equal to 6.35 mm)