[WARNING] Unknown Ptg 3c (60) at cell (499,0)

[Karl-Heinz Zengerle]

Hi world.
 
After I can process files now of about 4 MB I see the following
messages. The things still run wonderful.
 
 
[WARNING] Unknown Ptg 3c (60) at cell (499,0)
[WARNING] Unknown Ptg 3c (60) at cell (499,1)
[WARNING] Unknown Ptg 3c (60) at cell (499,2)
 
Does anybody know what this indicates? Is it fully harmless or might it
also cause crashes sometimes?
 
Recently there was another "Unknown Ptg" question in the POI list but
that seems to be fully different.
 
Regards,
Karl-Heinz Zengerle