diff --git a/lib/libsys/clock_gettime.2 b/lib/libsys/clock_gettime.2
index 82f6615e8b93..fcdc5be498f2 100644
--- a/lib/libsys/clock_gettime.2
+++ b/lib/libsys/clock_gettime.2
@@ -1,209 +1,227 @@
 .\"	$OpenBSD: clock_gettime.2,v 1.4 1997/05/08 20:21:16 kstailey Exp $
 .\"
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-.Dd October 27, 2023
+.Dd June 28, 2024
 .Dt CLOCK_GETTIME 2
 .Os
 .Sh NAME
 .Nm clock_gettime ,
 .Nm clock_settime ,
 .Nm clock_getres
 .Nd get/set/calibrate date and time
 .Sh LIBRARY
 .Lb libc
 .Sh SYNOPSIS
 .In time.h
 .Ft int
 .Fn clock_gettime "clockid_t clock_id" "struct timespec *tp"
 .Ft int
 .Fn clock_settime "clockid_t clock_id" "const struct timespec *tp"
 .Ft int
 .Fn clock_getres "clockid_t clock_id" "struct timespec *tp"
 .Sh DESCRIPTION
 The
 .Fn clock_gettime
 and
 .Fn clock_settime
 system calls allow the calling process to retrieve or set the value
 used by a clock which is specified by
 .Fa clock_id .
 .Pp
 The
 .Fa clock_id
 argument can be a value obtained from
 .Xr clock_getcpuclockid 3
 or
 .Xr pthread_getcpuclockid 3
 as well as the following values:
 .Pp
 .Bl -tag -width indent -compact
 .It Dv CLOCK_REALTIME
 .It Dv CLOCK_REALTIME_PRECISE
 .It Dv CLOCK_REALTIME_FAST
 .It Dv CLOCK_REALTIME_COARSE
-Increments as a wall clock should.
+Increments in SI seconds like a wall clock.
+It uses a 1970 epoch and implements the UTC timescale.
+The count of physical SI seconds since 1970, adjusted by subtracting the number
+of positive leap seconds and adding the number of negative leap seconds.
+Behavior during a leap second is not defined by and POSIX standard.
 .It Dv CLOCK_MONOTONIC
 .It Dv CLOCK_MONOTONIC_PRECISE
 .It Dv CLOCK_MONOTONIC_FAST
 .It Dv CLOCK_MONOTONIC_COARSE
-Increments in SI seconds.
+.It Dv CLOCK_BOOTTIME
+Increments in SI seconds, even while the system is suspended.
+Its epoch is unspecified.
+The count is not adjusted by leap seconds.
+.Fx implements
 .It Dv CLOCK_UPTIME
 .It Dv CLOCK_UPTIME_PRECISE
 .It Dv CLOCK_UPTIME_FAST
-.It Dv CLOCK_BOOTTIME
-Starts at zero when the kernel boots and increments
-monotonically in SI seconds while the machine is running.
+Increments monotonically in SI seconds while the machine is running.
+The count is not adjusted by leap seconds.
+The epoch is unspecified.
 .It Dv CLOCK_VIRTUAL
 Increments only when
 the CPU is running in user mode on behalf of the calling process.
 .It Dv CLOCK_PROF
 Increments when the CPU is running in user or kernel mode.
 .It Dv CLOCK_SECOND
 Returns the current second without performing a full time counter
 query, using an in-kernel cached value of the current second.
 .It Dv CLOCK_PROCESS_CPUTIME_ID
 Returns the execution time of the calling process.
 .It Dv CLOCK_THREAD_CPUTIME_ID
 Returns the execution time of the calling thread.
 .El
 .Pp
 The clock IDs
+.Dv CLOCK_BOOTTIME ,
 .Dv CLOCK_REALTIME ,
 .Dv CLOCK_MONOTONIC ,
 and
 .Dv CLOCK_UPTIME
 perform a full time counter query.
 The clock IDs with the _FAST suffix, i.e.,
 .Dv CLOCK_REALTIME_FAST ,
 .Dv CLOCK_MONOTONIC_FAST ,
 and
 .Dv CLOCK_UPTIME_FAST ,
 do not perform
 a full time counter query, so their accuracy is one timer tick.
 Similarly,
 .Dv CLOCK_REALTIME_PRECISE ,
 .Dv CLOCK_MONOTONIC_PRECISE ,
 and
 .Dv CLOCK_UPTIME_PRECISE
 are used to get the most exact value as possible, at the expense of
 execution time.
 The clock IDs
 .Dv CLOCK_REALTIME_COARSE
 and
 .Dv CLOCK_MONOTONIC_COARSE
 are aliases of corresponding IDs with _FAST suffix for compatibility with other
 systems.
 Finally,
 .Dv CLOCK_BOOTTIME
 is an alias for
-.Dv CLOCK_UPTIME
+.Dv CLOCK_MONOTONIC
 for compatibility with other systems and is unrelated to the
 .Fa kern.boottime
 .Xr sysctl 8 .
 .Pp
 The structure pointed to by
 .Fa tp
 is defined in
 .In sys/timespec.h
 as:
 .Bd -literal
 struct timespec {
 	time_t	tv_sec;		/* seconds */
 	long	tv_nsec;	/* and nanoseconds */
 };
 .Ed
 .Pp
 Only the super-user may set the time of day, using only
 .Dv CLOCK_REALTIME .
 If the system
 .Xr securelevel 7
 is greater than 1 (see
 .Xr init 8 ) ,
 the time may only be advanced.
 This limitation is imposed to prevent a malicious super-user
 from setting arbitrary time stamps on files.
 The system time can still be adjusted backwards using the
 .Xr adjtime 2
 system call even when the system is secure.
 .Pp
 The resolution (granularity) of a clock is returned by the
 .Fn clock_getres
 system call.
 This value is placed in a (non-NULL)
 .Fa *tp .
 .Sh RETURN VALUES
 .Rv -std
 .Sh ERRORS
 The following error codes may be set in
 .Va errno :
 .Bl -tag -width Er
 .It Bq Er EINVAL
 The
 .Fa clock_id
 or
 .Fa timespec
 argument
 was not a valid value.
 .It Bq Er EPERM
 A user other than the super-user attempted to set the time.
 .El
 .Sh SEE ALSO
 .Xr date 1 ,
 .Xr adjtime 2 ,
 .Xr clock_getcpuclockid 3 ,
 .Xr ctime 3 ,
 .Xr pthread_getcpuclockid 3
 .Sh STANDARDS
 The
 .Fn clock_gettime ,
 .Fn clock_settime ,
 and
 .Fn clock_getres
 system calls conform to
-.St -p1003.1b-93 .
+.St -p1003.1-2008 .
 The clock IDs
-.Dv CLOCK_REALTIME_FAST ,
-.Dv CLOCK_REALTIME_PRECISE ,
+.Dv CLOCK_BOOTTIME ,
 .Dv CLOCK_MONOTONIC_FAST ,
 .Dv CLOCK_MONOTONIC_PRECISE ,
+.Dv CLOCK_REALTIME_FAST ,
+.Dv CLOCK_REALTIME_PRECISE ,
+.Dv CLOCK_SECOND
 .Dv CLOCK_UPTIME ,
 .Dv CLOCK_UPTIME_FAST ,
-.Dv CLOCK_UPTIME_PRECISE ,
-.Dv CLOCK_SECOND
+and
+.Dv CLOCK_UPTIME_PRECISE
 are
 .Fx
 extensions to the POSIX interface.
+.Pp
+UTC is defined by ITU-R TF.460-6, Standard-frequency and time-signal emissions.
+However, the
+.Vt time_t
+type is a simple count that does not provide a unique encoding for leap seconds,
+nor a specification for what values should be used to encode a leap second.
+.Pp
 .Sh HISTORY
 The
 .Fn clock_gettime ,
 .Fn clock_settime ,
 and
 .Fn clock_getres
 system calls first appeared in
 .Fx 3.0 .