Index: changes.md
==================================================================
--- changes.md
+++ changes.md
@@ -8,11 +8,10 @@
 
 ## Changes since Tcl 9.0.0
  - [zlib-8.8, zlib-8.16 fail on Fedora 40, gcc 14.1.1](https://core.tcl-lang.org/tcl/tktview/73d5cb)
  - [regression in tzdata, %z instead of offset TZ-name](https://core.tcl-lang.org/tcl/tktview/2c237b)
  - [Tcl will not start properly if there is an init.tcl file in the current dir](https://core.tcl-lang.org/tcl/tktview/43c94f)
- - [clock scan of leapsecond: wrong result](https://core.tcl-lang.org/tcl/tktview/f2b5f8)
  - [clock scan "24:00", ISO-8601 compatibility](https://core.tcl-lang.org/tcl/tktview/aee9f2)
  - [install registry and dde in $INSTALL_DIR\lib always](https://core.tcl-lang.org/tcl/tktview/364bd9)
  - [cannot build .chm help file (Windows)](https://core.tcl-lang.org/tcl/tktview/bb110c)
  - [TIP 701 - Tcl_FSTildeExpand C API](https://core.tcl-lang.org/tips/doc/trunk/tip/701.md)
  - [buffer overwrite for non-BMP characters in utf-16](https://core.tcl-lang.org/tcl/tktview/66da4d)

Index: doc/clock.n
==================================================================
--- doc/clock.n
+++ doc/clock.n
@@ -919,11 +919,12 @@
 A time of day, which is of the form:
 .QW "\fIhh\fR?\fB:\fImm\fR?\fB:\fIss\fR?? ?\fImeridian\fR? ?\fIzone\fR?"
 or
 .QW "\fBhhmm \fR?\fBmeridian\fR? ?\fBzone\fR?" .
 If no \fImeridian\fR is specified, \fIhh\fR is interpreted on
-a 24-hour clock.
+a 24-hour clock. The "24:00" and "24:00:00" formats (with or without
+colon) are supported only if no \fImeridian\fR is specified.
 .TP
 \fIdate\fR
 .
 A specific month and day with optional year.  The
 acceptable formats are
@@ -949,11 +950,13 @@
 .QW "\fICCyymmdd\fBT\fIhh:mm:ss\fR" ,
 or
 .QW "\fICCyy-mm-dd\fBT\fIhh:mm:ss\fR" .
 Note that only these four formats are accepted.
 The command does \fInot\fR accept the full range of point-in-time
-specifications specified in ISO8601.  Other formats can be recognized by
+specifications specified in ISO8601.  For example, leap seconds are
+not supported. The "24:00" and "24:00:00" formats (with or without
+colon) are supported.  Other formats can be recognized by
 giving an explicit \fB\-format\fR option to the \fBclock scan\fR command.
 .TP
 \fIrelative time\fR
 .
 A specification relative to the current time.  The format is \fBnumber

Index: generic/tclClock.c
==================================================================
--- generic/tclClock.c
+++ generic/tclClock.c
@@ -3783,11 +3783,10 @@
     int stage)			/* Stage to validate (1, 2 or 3 for both) */
 {
     const char *errMsg = "", *errCode = "";
     TclDateFields temp;
     int tempCpyFlg = 0;
-    int leapDay = -1;
     ClockClientData *dataPtr = opts->dataPtr;
 
 #if 0
     printf("yyMonth %d, yyDay %d, yyDayOfYear %d, yyHour %d, yyMinutes %d, yySeconds %" TCL_LL_MODIFIER "d, "
 	    "yySecondOfDay %" TCL_LL_MODIFIER "d, sec %" TCL_LL_MODIFIER "d, daySec %" TCL_LL_MODIFIER "d, tzOffset %d\n",
@@ -3808,24 +3807,18 @@
 		    || yydate.iso8601Year > dataPtr->validMaxYear) {
 		errMsg = "invalid iso year";
 		errCode = "iso year";
 		goto error;
 	    }
-	    if ((yydate.iso8601Year < 1972) || (yydate.iso8601Year > 2017)) {
-		leapDay = 0;
-	    }
 	}
 	if (info->flags & CLF_YEAR) {
 	    if (yyYear < dataPtr->validMinYear
 		    || yyYear > dataPtr->validMaxYear) {
 		errMsg = "invalid year";
 		errCode = "year";
 		goto error;
 	    }
-	    if ((yyYear < 1972) || (yyYear > 2017)) {
-		leapDay = 0;
-	    }
 	} else if ((info->flags & CLF_ISO8601YEAR)) {
 	    yyYear = yydate.iso8601Year; /* used to recognize leap */
 	}
 	if ((info->flags & (CLF_ISO8601YEAR | CLF_YEAR))
 		== (CLF_ISO8601YEAR | CLF_YEAR)) {
@@ -3840,36 +3833,18 @@
     if (info->flags & CLF_MONTH) {
 	if (yyMonth < 1 || yyMonth > 12) {
 	    errMsg = "invalid month";
 	    errCode = "month";
 	    goto error;
-	} else if (leapDay) {
-	    switch (yyMonth) {
-	    case 6:
-		leapDay = 30;
-		break;
-	    case 12:
-		leapDay = 31;
-		break;
-	    case 1:
-	    case 7:
-		leapDay = 1;
-		break;
-	    default:
-		leapDay = 0;
-		break;
-	    }
 	}
     }
     /* day of month */
     if (info->flags & (CLF_DAYOFMONTH|CLF_DAYOFWEEK)) {
 	if (yyDay < 1 || yyDay > 31) {
 	    errMsg = "invalid day";
 	    errCode = "day";
 	    goto error;
-	} else if ((leapDay > 0) && (info->flags & CLF_DAYOFMONTH) && (yyDay != leapDay)) {
-	    leapDay = 0;
 	}
 	if ((info->flags & CLF_MONTH)) {
 	    const int *h = hath[IsGregorianLeapYear(&yydate)];
 
 	    if (yyDay > h[yyMonth - 1]) {
@@ -3907,23 +3882,19 @@
 	/* hour */
 	if (yyHour < 0 || yyHour > ((yyMeridian == MER24) ? 24 : 12)) {
 	    errMsg = "invalid time (hour)";
 	    errCode = "hour";
 	    goto error;
-	} else if (yyHour == 24) {
-	    leapDay = 0;
 	}
 	/* minutes */
 	if (yyMinutes < 0 || yyMinutes > 59 || (yyMinutes && (yyHour == 24))) {
 	    errMsg = "invalid time (minutes)";
 	    errCode = "minutes";
 	    goto error;
-	} else if ((yyMinutes % 15) != 14) {
-	    leapDay = 0;
 	}
 	/* oldscan could return secondOfDay (parsedTime) -1 by invalid time (ex.: 25:00:00) */
-	if (yySeconds < 0 || yySeconds > (leapDay ? 60 : 59) || yySecondOfDay <= -1 || (yySeconds && (yyHour == 24))) {
+	if (yySeconds < 0 || yySeconds > 59 || yySecondOfDay <= -1 || (yySeconds && (yyHour == 24))) {
 	    errMsg = "invalid time";
 	    errCode = "seconds";
 	    goto error;
 	}
     }

Index: tests/clock.test
==================================================================
--- tests/clock.test
+++ tests/clock.test
@@ -38459,13 +38459,12 @@
     set res; # must be empty
 } -result {}
 test clock-68.1a {Leap second, minute, hour [f2b5f89c0d], regression test (validity check)} -body {
     set res {}
     foreach {d i} {
-	"2012-06-30 23:59:60" 1341100800
 	"2012-06-30 24:00:00" 1341100800
-    } {
+        } {
 	# check with free scan:
 	if {[set t [clock scan $d -gmt 1]] != $i} {
 	    lappend res "free-scan \"$d\" == $t, expected $i"
 	}
 	# check with formatted scan:
@@ -38473,23 +38472,23 @@
 	    lappend res "fmt-scan \"$d\" == $t, expected $i"
 	}
     }
     set res; # must be empty
 } -result {}
-test clock-68.2 {Leap second, minute, hour [f2b5f89c0d], regression test (validity check)} -constraints !valid_off -body {
-    # regardless solution for [f2b5f89c0d], this conversions must fail on -valid 1 (constraints !valid_off),
-    # because of wrong day and month for the leap second. There were only leap seconds from 1972 - 2016:
+test clock-68.2 {Leap second, "24:00", regression test (validity check)} -constraints !valid_off -body {
+    # Leap seconds are not supported. "24:00" is supported.
     set res {}
     foreach {d i} {
 	"2012-06-29 23:59:60" "invalid time"
 	"2012-05-30 23:59:60" "invalid time"
 	"2012-05-30 23:60:60" "invalid time"
 	"2012-05-30 24:00:01" "invalid time"
 	"2012-05-30 24:01:00" "invalid time"
 	"1971-06-30 23:59:60" "invalid time"
+	"2012-06-30 23:59:60" "invalid time"
 	"2018-06-30 23:59:60" "invalid time"
-    } {
+        } {
 	# check with free scan:
 	if {![catch { clock scan $d -gmt 1 } t] || ![string match *$i* $t]} {
 	    lappend res "free-scan \"$d\" == \"$t\", expected \"$i\""
 	}
 	# check with formatted scan: