I am in the process of backing up a bunch of CDs. I have been using the following command to do so:

dd if=/dev/cdrom of=/media/sdb/filename.iso
I've noticed that in most of the .ISO images created this way (nearly all), when mounted using Archive Mounter or when viewed using Archive Manager, every file has ;1 at the end of the filename after the appropriate file extension.

1. What is the purpose of this ;1 extension?
2. Is there an argument I can use to stop dd from creating this extension?
3. And is dd the best for backing up CDs to an image file? (As far as reliability goes)

The problem is that I'm mounting the .ISO images as a virtual drive (instead of burning a copy of every disk I use), but the ;1 at the end of every file doesn't allow the files to be opened/executed with a double-click because nautilus does not recognize the type of file.

Any help is always greatly appreciated =)
- SlimBiggins