/BLOCKS={(START:n, COUNT:x, END:y,) FILE_SYSTEM, ALL}

    Directs the system to compare only the range specified. The
    options are the following:

    START:n     Number of the first block to be analyzed. The default
                is the first block.

    COUNT:x     Number of blocks to be analyzed. You can use this
                option in combination with or instead of the END
                option.

    END:y       Number of the last block to be analyzed. The default
                is the last block of the volume.

    FILE_       Blocks currently in use by valid files on the disk.
    SYSTEM      This is the default.

    ALL         All blocks on the disk.

    You can specify START,END,COUNT and either ALL or FILE_SYSTEM.
    For example, if you specify /BLOCKS=(START,END,COUNT:100,ALL),
    the software checks the first 100 blocks on the disk, whether or
    not the file system is using them.

    If you specify /BLOCKS=(START,END,COUNT:100,FILE_SYSTEM), the
    software checks only those blocks that valid files on the disk
    are using.