[ns] what is invalid command "PLevels"

[Nikheel Kumar]

*hello friends,

here some lines of tcl script to access different wireless scenario:*



set mode        DCF                ;# mode for this test DCF/PCF
set pcf_period        0                ;# CFP period for pcf mode
set pcf_duration    0                ;# CFP duration for pcf mode
set endtime        15.0                ;# duration of the simulation
set title_        "snenario-test"                ;# default title for the
scenario
set idea_mac        0                ;# default cleverness of mac
                            ;#     0 - normal
                            ;#     1 - persistent slotting
                            ;#     0 - PDCF

set val(chan)        Channel/WirelessChannel        ;# Channel Type
set val(prop)        Propagation/TwoRayGround    ;# radio-propagation model
set val(netif)        Phy/WirelessPhy            ;# network interface type
set val(mac)        Mac/802_11            ;# MAC type
set val(ifq)        Queue/DropTail/PriQueue        ;# interface queue type
set val(ll)        LL                ;# link layer type
set val(ant)        Antenna/OmniAntenna        ;# antenna model
set val(ifqlen)        50                ;# max packet in ifq
set val(rp)        DSDV                ;#
set val(x)        50
set val(y)        50

Phy/WirelessPhy set CPThresh_    2000
Phy/WirelessPhy set per_    0.0
Mac/802_11 set bandwidth_    36Mb
PLevels set max_plevels_    8
PLevels set plevels_        8
MAC_MIB set RTSThreshold_    3000
MAC_MIB set ShortRetryLimit_    7
MAC_MIB set LongRetryLimit_    4
PHY_MIB set MinimumBandwidth_    6Mb
PHY_MIB set SlotTime_        0.000009
PHY_MIB set SIFS_        0.000016
.....
......
......

*i got following error:-*

$ ns main.tcl
invalid command name "PLevels"
          while executing
"PLevels set max_plevels_      8"

*what is this error for????
plz help me*