@
tlfamm - In Windows you can add a .URL file much as you can add a .LNK file. For some reason if I try to add it via
Add Books->Add files to selected book records it doesn't seem to work.
Also note that .LNK files have a problem with
Add Books->Add files to selected book records. Windows jumps in and opens the .LNK target

Yet another instance of software being a Nanny and assuming it knows best
But you can drag-and-drop a URL file into the Book List and it will create a new book, if you have a shortcut to calibre in your Send To folder you can send the .URL file to calibre (good for the mouse averse) - you can do the same with .LNK files.
@
eschwartz - its probably no use to you, but the attached zip contains a Windows .URL file to the calibre user manual - you could try dropping the URL onto your test library - probably need to unarchive the zip first.
BR