''The following proc converts an integer number of seconds to culture-dependent units (days, hrs, mins, secs) specification. From a news:comp.lang.tcl posting by David Gravereaux:''

Here's a duration proc I wrote that should give you a better sense of what I think your asking 'clock format' for:

 % proc duration { int_time } {
     set timeList [list]
     foreach div {86400 3600 60 1} mod {0 24 60 60} name {day hr min sec} {
         set n [expr {$int_time / $div}]
         if {$mod > 0} {set n [expr {$n % $mod}]}
         if {$n > 1} {
             lappend timeList "$n ${name}s"
         } elseif {$n == 1} {
             lappend timeList "$n $name"
         }
     }
     return [join $timeList]
 }
 % duration 67
 1 min 7 secs

----
For a version of the same that handles floats and avoids OCTAL, see:

 http://inferno.slug.org/cgi-bin/wiki/duration
----
 * David Gravereaux *
 Tomahawk Software Group

''Updated by DKF''
----
'''Culture-independent hh:mm:ss notation''' by RS:
 proc hh:mm:ss {secs} {
	set h [expr {$secs/3600}]
	incr secs [expr {$h*-3600}]
	set m [expr {$secs/60}]
	set s [expr {$secs%60}]
	format "%02.2d:%02.2d:%02.2d" $h $m $s
 }
 hh:mm:ss 67
 00:01:07
----
Oops, forget it. Tcl has it built in (if you force GMT):
 clock format 67 -gmt 1 -format %H:%M:%S   ;#RS
 00:01:07