I've noticed that files that are converted from v6 to v7 convert with a syntax like this:

file:FileName

The help file shows this to be the proper syntax:

file:FileName.fp7

Both ways seem to work but I would think that it would be better to explicitly identify the file name including the extension. On the other hand, maybe this is a way of keeping solutions non-version specific. Any thoughts?

If you go into your Control Panels in XP, select Folder Option and then the View tab. The item "Hide extensions for known file types" is probably checked. This will suppress the .ext when displaying the files in your folder.

That's not it. I'm talking about from within FileMaker itself:

File -> Define -> File References...

It allows entries either with or without the file extension. I was just curious if someone knew of an advantage either way.

This behavior is described in the conversion documentation. I don't think there's any difference from FileMaker's point of view. I mean, it can only have FileMaker 7 files as relational references; no other kind of documents, so the extension is superfluous.