Some Observations on "Arm Hollows"

[Koen G]

It could be, though one could also see these examples as a somewhat forced/awkward attempt to convey that the arm is exactly on top of the rim in the back. Basically we can't say this for sure before we answer these questions:

• Do the patterns have a significance, and if so, which one?
  
• Does the pose of the human figures have a significance, and if so, which one? 
  
• Does the relation between the limbs of the figures and other objects have a significance, and if so, which one?
  

Before we know more about these things, it's hard to say whether the pattern serves the sole purpose of making sure that we see where the inside of the barrel ends compared to the arms, or whether the pattern being there has a significance of its own. Or whether it's just a mixed-perspective attempt to reder the three-dimensionality of the barrel... 

All are still possible, I think, but keeping an eye open for things like this might help us along.