SYS the c: drive

What does “SYS the c: drive” mean?
I’m getting ready to format my hard drive to do a clean install of Windows 2000 Professional.
Paul Thurrott writes:

The first step, then, involves booting the system with the boot floppy. If you’re using a Windows 98 floppy, do not enable CD-ROM support. When the command prompt comes up, use FDISK to create one or more partitions on the hard drive. Then, reboot the system, choose CD-ROM support if you are using a Windows 98 boot floppy, and format the hard drive (at least the C: drive) from the command line. When this is complete, SYS the C: drive so it boots: While this isn’t always necessary, on several occasions I’ve seen the Windows 2000 install process halt because it couldn’t boot the C: drive during the first reboot.

Thanks