"ntp-refclock"

Definition: ntp-refclock: NTP v4 daemon for reference clocks. This version of the ntp daemon includes drivers to interface to various radio clocks and other devices used for creating reference clocks. If you do not have a radio clock, use the ntp-simple package instead, as it consumes far less memory! If you're serious about building a high-quality stratum 1 timekeeper, please take a look at Ulrich Windl's PPSkit patchset for the Linux kernel, available from the kernel.org mirror network in pub/linux/daemons/ntp. From Debian 3.0r0 APT

* Linux/Unix/Computing Glossary