Why is this a problem? Because if you want to measure from the edge of the board and it's the left side of the board it will be in inches (imperial) but if you measure the right side of course you flip the square and it's now metric. I like both metric and imperial systems, but I NEVER use both systems in the same project. You should check every few minutes. Insane. Make them either metric or imperial, but not both at the same time!