Units

We start with an optional units clause, where we can define units to use in relative calculations.
The four predefined ones are U, u, cx, and cy.

U: 19.05 # 19.05 MX spacingu: 19 # 19mm MX spacingcx: 18 # 18mm Choc X spacingcy: 17 # 17mm Choc Y spacing

But we can add any other (or modify these predefined ones), or even use an existing measure in calculating a new value (for example, double: 2 u). Recall how each string that can be interpreted as a math formula will be treated like a number, so this is a great way to add math-level variables to your config.

units:  a: cy - 7  b: a * 1.5