Hi @Anonymous 

At first I have to mention that AutoCAD knows nothing about centimeters or millimeters. It knows only about units (AutoCAD drawing units). And you can decide how long is this AutoCAD drawing unit, it could be mm, cm, m, km, etc.

>>>>>How does the xp factor scale work?

Entering a value followed by xp, indicates the scale relative to paper space units. For example, entering 1000/100xp=10xp displays model space at ten times of the scale of paper space units and set viewport scale to 10:1.

In your case the size of paper is 59.4 x 42.00 AutoCAD units (you think they are cm), so when you set viewport scale to 10:1, and viewport occupies entire sheet, you could fit object in Model space with dimensions not more than 5.94 x 4.2 AutoCAD drawing units.