Can a chainstay's length vary? My gut is telling me that this is a typo, but here's what I'm seeing.

I'm looking at the 2017 Rocky Mountain Element which seems to feature a chainstay that can range from 439-437mm. 

For comparison, the 2017 Rocky Mountain Instinct, seem to feature a fixed chainstay length of 452mm.

For the other parts of the geometry that have a range, I get why for these as the suspension compresses and changes the value. However, I can't see how the chainstay would change in length in this case.
Apparently, there are differences not readily apparent on the frame graphics. Per Rocky Mountain:


  The decision to include variable rear center information on the
  Element relates to the redesigned linkage, hence why the Instinct
  doesn’t show any change. The rearmost pivot is much closer to the rear
  axle on the Instinct, so the change is virtually nonexistent.