Help: a stupid question :P

[Hung-Kei Keith Chow <keith@europa.nal.utoronto.ca>]

Hi,

I'm a newbie in both ns and tcl.
Please excuse me if my question sounds stupid.

I 've a problem understanding the command "target" found in some tcl scripts.
For example, in "fq.tcl", we have:

FQLink instproc init { src dst bw delay nullAgent } {
......
        set drpT_ $nullAgent
        set nactive_ 0
        set queue_ [new Queue/FQ]
        set link_ [new DelayLink]
        $link_ set bandwidth_ $bw
        $link_ set delay_ $delay
....
        $queue_ target $link_
                ^^^^^^
        $queue_ drop-target $nullAgent
        $link_ target [$toNode_ entry]
               ^^^^^^
.....

What does "target" really do?
Is it a tcl command? But I can't find it in my manual.
If not, where is it defined?
Please advice.

Thanks for your help.

Keith.