If start-byte and/or length are given, they specify the start offset address and number of bytes to write respectively; otherwise, the whole image is copied.
If -save-craff is specified, data is saved in craff format, using compression unless -u is specified. If -save-raw is specified, data is saved in raw format, which is also the default option. If -save-vhdx is specified, data is saved in VHDX format.
The command will fail if the destination file already exists, unless -overwrite is specified.