After quickly writing a MolFile generator for some fictional structures, the generated MolFile strings load acceptably in Jmol but produce several error lines containing '0 0' is not a recognized symbol.

Any idea why? Here's an example file:

unknown
NDB/matchbOx/03022013221425

 4 4 0 0 0 0 0 0 0 0 1 V2000
   0.0000 0.0000 0 C 0 0 0 0 0 0 0 0 0 0 0 0
   0.0000 1.0000 0 C 0 0 0 0 0 0 0 0 0 0 0 0
   1.0000 0.0000 0 C 0 0 0 0 0 0 0 0 0 0 0 0
   1.0000 1.0000 0 C 0 0 0 0 0 0 0 0 0 0 0 0
 1 4 1 0 0 0 0
 1 2 1 0 0 0 0
 2 3 1 0 0 0 0
 3 4 1 0 0 0 0
M END
$$$$

Even the cited benzene example here generates a '' is not a recognized symbol.

David