Linedef 0?

I searched Google for the answer, but to no avail, and I can't search the forums since you can't include search terms that are less than three characters, so sorry if this has been asked already.

But what exactly is Linedef 0? Mainly I'd like to know how it causes this and intercepts overflows.

Linedef type 0 is just the setting used for "normal" linedefs that don't do anything.

ultdoomer said:

...But what exactly is Linedef 0?...

The very first linedef in a map.

And if you are thinking of Linedef type 0, well Fraggle is correct.