Comment 2 for bug 733635

One problem with (4) is that if pcb is choking on a file, it can't know how or why it is --- naturally, the format changes will have occurred after its release date.

In a couple versions we will change the format to allow unit suffixes. Current git HEAD can handle this already, but 20100929 cannot. (In fact, 20100929 has broken support for nm/um units and there is a potential for Bad Things to happen rather than a simple parse error.) Plus, the measures-versus-numbers mess we had when introducing this unit support shows how inflexible the parser can be. These are the kind of problems we have now.

I agree that a warning should pop up rather than the frightening "blank pcb with no warning" we have now, but I think that's all we can do at this point.

In the distant future we hope to have an extensible file format -- then we can be much smarter about recognizing unknown fields, estimating the severity of incompatibilities, recovery/repair, not trampling user-edited text data, etc.