Irule syntax issue : missing a script

 I just test the syntax and it works.
 Remember: 
 Trim the end of each line, indent the beginning for best pratices 
 and write the conditions with curly braces.

 To paste the code on this forum, start each line with {tab} character

when HTTP_REQUEST {

    set secs [clock seconds]
    set msec [clock clicks -milliseconds]
    set base [expr { $secs * 1000 } ]
    set fract [expr { $msec - $base }]

    log local0. "step_1 $fract"

    if {$fract >= 1000 } {
        set diff [expr { $fract / 1000 }]
        incr secs $diff
        incr fract [expr { -1000 * $diff }]
    }

    log local0. "step_2 $fract"

    if {[$fract matches_regex "\d\d"]} {
        append fract 0
    }
    elseif {$fract matches_regex {/\d} } {
        append fract 00
    }

    log local0. "Timestamp with milliseconds is $secs.$fract"
}