Why is Inventor in centimeters when programming in VBA ?

Why is it that if you program in vba, a value for example 10, for inventor this is 10 cm?
Why is this not inche?
Since this is American, I really do not understand that a variable value is in centimeters.
Dim Inch As Double
Inch = 2.54
Dim PipeLength As Double
PipeLength = 100
'Creating a circles (text)
Call oSketch.SketchCircles.AddByCenterRadius (oTG.CreatePoint2d (0, 0), (OD / 2 * Inch))