cyli2.dat

[Lasse Deleuran]

The other confusion is that the rule that is written—i.e., the official library spec—expressly says that conditional lines may not overlap, even in part. However, it could be interpreted that this refers only to condlines within the same file; that is, not to condlines in different (sub)files that happen to overlap. Might be something worth clarifying.

That the lines belong to different files makes no difference for the rendering.
As we do not have normal, nor UV information in the data format, renders have to rely on the information gathered from lines and conditional lines in order to ensure smooth surfaces where expected. However. Overlying conditional lines and conditional lines that intersect wit normal lines cause artefacts, such as seen on the macaroni bricks. 

Example. Click "3D" and zoom in on the outer curve of a macaroni brick. The UV calculation above the indent for the stud fails and causes the surface to break. This is due to a conditional line and a normal line overlapping.