Root Delay (sys.rootdelay, peer.rootdelay, pkt.rootdelay): This is a
signed fixed-point number indicating the total roundtrip delay to the
primary reference source at the root of the synchronization subnet, in
seconds. Note that this variable can take on both positive and negative
values, depending on clock precision and skew.

Root Dispersion (sys.rootdispersion, peer.rootdispersion,
pkt.rootdispersion): This is a signed fixed-point number indicating the
maximum error relative to the primary reference source at the root of
the synchronization subnet, in seconds. Only positive values greater
than zero are possible.

Reference Clock Identifier (sys.refid, peer.refid, pkt.refid): This is a
32-bit code identifying the particular reference clock. In the case of
stratum 0 (unspecified) or stratum 1 (primary reference source), this is
a four-octet, left-justified, zero-padded ASCII string, for example (see
Appendix A for comprehensive list):

@Z_TBL_BEG = COLUMNS(3), DIMENSION(IN), COLWIDTHS(E2,E2,E5),
WIDTH(4.1700), ABOVE(.1670), BELOW(.0830), HGUTTER(.3330),
BOX(Z_SINGLE), KEEP(ON), ALIGN(CT), L1(R1C0..R1C3)

@Z_TBL_BODY = TABLE CENTER, TABLE HEADER, TABLE HEADER

Stratum, Code, Meaning

@Z_TBL_BODY = TABLE CENTER, TABLE TEXT, TABLE TEXT

0, DCN, DCN routing protocol

0, TSP, TSP time protocol

1, ATOM, Atomic clock (calibrated)

1, WWVB, WWVB LF (band 5) radio

1, GOES, GOES UHF (band 9) satellite

@Z_TBL_BODY = TABLE CENTER, TABLE HEADER, TABLE HEADER

1, WWV, WWV HF (band 7) radio

@Z_TBL_END =

In the case of stratum 2 and greater (secondary reference) this is the
four-octet Internet address of the peer selected for synchronization.

Reference Timestamp (sys.reftime, peer.reftime, pkt.reftime): This is
the local time, in timestamp format, when the local clock was last
updated. If the local clock has never been synchronized, the value is
zero.

Originate Timestamp (peer.org, pkt.org): This is the local time, in
timestamp format, at the peer when its latest NTP message was sent. If
the peer becomes unreachable the value is set to zero.

Receive Timestamp (peer.rec, pkt.rec): This is the local time, in
timestamp format, when the latest NTP message from the peer arrived. If
the peer becomes unreachable the value is set to zero.

Transmit Timestamp (peer.xmt, pkt.xmt): This is the local time, in
timestamp format, at which the NTP message departed the sender.

System Variables

Table 1<$&tab1> shows the complete set of system variables. In addition
to the common variables described previously, the following variables
are used by the operating system in order to synchronize the local
clock.

Local Clock (sys.clock): This is the current local time, in timestamp
format. Local time is derived from the hardware clock of the particular
machine and increments at intervals depending on the design used. An
appropriate design, including slewing and skew-Compensation mechanisms,
is described in Section 5.

Clock Source (sys.peer): This is a selector identifying the current
synchronization source. Usually this will be a pointer to a structure
containing the peer variables. The special value NULL indicates there is
no currently valid synchronization source.

Peer Variables

Table 2 shows the complete set of peer variables. In addition to the
common variables described previously, the following variables are used
by the peer management and measurement functions.

Configured Bit (peer.config): This is a bit indicating that the
association was created from configuration information and should not be
demobilized if the peer becomes unreachable.

Update Timestamp (peer.update): This is the local time, in timestamp
format, when the most recent NTP message was received. It is used in
calculating the skew dispersion.

Reachability Register (peer.reach): This is a shift register of
NTP.WINDOW bits used to determine the reachability status of the peer,
with bits entering from the least significant (rightmost) end. A peer is
considered reachable if at least one bit in this register is set to one.