.sp
\fBclock add\fR \fItimeVal\fR ?\fIcount unit...\fR? ?\fI\-option value\fR?
.sp
\fBclock clicks\fR ?\fI\-option\fR?
.sp
\fBclock format\fR \fItimeVal\fR ?\fI\-option value\fR...?
.sp
\fBclock microseconds\fR 
.sp
\fBclock milliseconds\fR 
.sp
\fBclock scan\fR \fIinputString\fR ?\fI\-option value\fR...?
.sp
\fBclock seconds\fR 
.sp
.BE
.SH "DESCRIPTION"
.PP
The \fBclock\fR command performs several operations that obtain and
manipulate values that represent times.  The command supports several
subcommands that determine what action is carried out by the command.

.RE
.TP
\fBclock format\fR \fItimeVal\fR ?\fI\-option value\fR...?
Formats a time that is expressed as an integer number of seconds into a format
intended for consumption by users or external programs.
See \fBFORMATTING TIMES\fR for a full description.
.TP
\fBclock microseconds\fR 
Returns the current time as an integer number of microseconds.  See \fBHIGH RESOLUTION TIMERS\fR for a full description.
.TP
\fBclock milliseconds\fR 
Returns the current time as an integer number of milliseconds.  See \fBHIGH RESOLUTION TIMERS\fR for a full description.
.TP
\fBclock scan\fR \fIinputString\fR ?\fI\-option value\fR...?
Scans a time that is expressed as a character string and produces an
integer number of seconds.
See \fBSCANNING TIMES\fR for a full description.
.TP
\fBclock seconds\fR 
Returns the current time as an integer number of seconds.
.SS "PARAMETERS"
.TP
\fIcount\fR
An integer representing a count of some unit of time.  See
\fBCLOCK ARITHMETIC\fR for the details.
.TP

interspersed with any number of \fIformat groups\fR, which are two-character
sequences beginning with the per-cent sign.  The permissible format groups,
and their interpretation, are described under \fBFORMAT GROUPS\fR.
.RS
.PP
On \fBclock format\fR, the default format is
.CS
%a %b %d %H:%M:%S %z %Y
.CE
.PP
On \fBclock scan\fR, the lack of a \fI\-format\fR option indicates that a
.QW "free format scan"
is requested; see \fBFREE FORM SCAN\fR for a description of what happens.
.RE
.TP

.TP
\fB%EE\fR
On output, produces the string \fBB.C.E.\fR or \fBC.E.\fR, or a
string of the same meaning in the locale, to indicate whether \fB%Y\fR refers
to years before or after Year 1 of the Common Era.  On input, accepts
the string \fBB.C.E.\fR, \fBB.C.\fR, \fBC.E.\fR, \fBA.D.\fR, or the
abbreviation appropriate to the current locale, and uses it to fix
whether \fB%Y\fR refers to years before or after Year 1 of the 
Common Era.
.TP
\fB%Ex\fR
On output, produces a locale-dependent representation of the date
in the locale's alternative calendar.  On input, matches
whatever \fB%Ex\fR produces.  The locale's alternative calendar need not
be the Gregorian calendar.

the first Thursday of the year (the three statements are
equivalent). Each week begins on a Monday. On input, accepts the
ISO8601 week number.
.TP
\fB%w\fR
On output, produces the ordinal number of the day of the week
(Sunday==0; Saturday==6).  On input, accepts a single digit and
interprets it as the day of the week; Sunday may be represented as 
either 0 or 7.  Note that \fB%w\fR is not the ISO8601 weekday number, 
which is produced and accepted by \fB%u\fR.
.TP
\fB%W\fR
On output, produces a week number (00-53) within the year; week 01
begins on the first Monday of the year. On input, accepts two digits,
which are otherwise ignored. This format group is never used in
determining an input date.  It is not the ISO8601 week number; that

A time zone specified in an environment variable \fBTZ\fR.
.IP [5]
The local time zone from the Control Panel on Windows systems.
.IP [6]
The C library's idea of the local time zone, as defined by the
\fBmktime\fR and \fBlocaltime\fR functions.
.PP
In case [1] \fIonly,\fR the string is tested to see if it is one 
of the strings:
.CS
 gmt     ut      utc     bst     wet     wat     at
 nft     nst     ndt     ast     adt     est     edt
 cst     cdt     mst     mdt     pst     pdt     yst
 ydt     hst     hdt     cat     ahst    nt      idlw
 cet     cest    met     mewt    mest    swt     sst
 eet     eest    bt      it      zp4     zp5     ist
 zp6     wast    wadt    jt      cct     jst     cast
 cadt    east    eadt    gst     nzt     nzst    nzdt
 idle
.CE
If it is a string in the above list, it designates a known
time zone, and is interpreted as such.
.PP
For time zones in case [1] that do not match any of the above strings, 
and always for cases [2]-[6], the following rules apply.
.PP
If the time zone begins with a colon, it is one of a
standardized list of names like \fB:America/New_York\fR
that give the rules for various locales.  A complete list
of the location names is too lengthy to be listed here.
On most Tcl installations, the definitions of the locations

Note that only these three 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
giving an explicit \fI\-format\fR option to the \fBclock scan\fR command.
.TP
\fIrelative time\fR
A specification relative to the current time.  The format is \fBnumber
unit\fR. Acceptable units are \fByear\fR, \fBfortnight\fR, 
\fBmonth\fR, \fBweek\fR, \fBday\fR,
\fBhour\fR, \fBminute\fR (or \fBmin\fR), and \fBsecond\fR (or \fBsec\fR).  The
unit can be specified as a singular or plural, as in \fB3 weeks\fR.
These modifiers may also be specified:
\fBtomorrow\fR, \fByesterday\fR, \fBtoday\fR, \fBnow\fR,
\fBlast\fR, \fBthis\fR, \fBnext\fR, \fBago\fR.
.PP