Can they be saved on either machine, copied back and forth, re-saved on either machine once more overwriting each other, re-copied back and forth... etc.? They seem to work, but I'm not 150% certain. I opened one up in a text editor and, aside from the Rudyard Kipling easter egg (), I really don't know what's going on under the hood and want to be sure there won't be any unexpected compatibility issues down the line.