Placing texture in a particle chain

OK, so the below script makes a lot of menus and a particle chain to an object. What I need to do is to create different textures for a particle chain. Any ideas how to do it?

Thanks

//leash script for the Open Collar Project (c)


integer targethandle;
vector pos = ZERO_VECTOR;
integer stay = FALSE;
integer listenhandle;

float length = 3.0;
string part_texture = "chain";
key part_target = NULL_KEY;
integer holderchannel = -8888;
key leasher = NULL_KEY;

integer lastrank;

//help
string parentmenu = "Main";
string submenu = "Leash";
list menulist;
integer menutimeout = 45; //i think it should be at least 45 seconds here if not for the post 60...
integer menulistener;
integer menuchannel = 1908789;
string currentmenu = "";

//MESSAGE MAP
integer COMMAND_NOAUTH = 0;
integer COMMAND_OWNER = 500;
integer COMMAND_SECOWNER = 501;
integer COMMAND_GROUP = 502;
integer COMMAND_WEARER = 503;
integer COMMAND_EVERYONE = 504;
//integer CHAT = 505;
integer COMMAND_SAFEWORD = 510; // new for safeword

//integer SEND_IM = 1000; deprecated. each script should send its own IMs now. This is to reduce even the tiny bt of lag caused by having IM slave scripts
integer POPUP_HELP = 1001;

integer HTTPDB_SAVE = 2000;//scripts send messages on this channel to have settings saved to httpdb
//str must be in form of "token=value"
integer HTTPDB_REQUEST = 2001;//when startup, scripts send requests for settings on this channel
integer HTTPDB_RESPONSE = 2002;//the httpdb script will send responses on this channel
integer HTTPDB_DELETE = 2003;//delete token from DB
integer HTTPDB_EMPTY = 2004;//sent when a token has no value in the httpdb

integer MENUNAME_REQUEST = 3000;
integer MENUNAME_RESPONSE = 3001;
integer SUBMENU = 3002;

string UPMENU = "~PrevMenu~";
string LEASH = "Grab";
string UNLEASH = "Unleash";
string STAY = "Stay";
string UNSTAY = "UnStay";
string L_LENGTH = "Length";
string GIVE_HOLDER = "give Holder";
string GIVE_POST = "give Post";
string REZ_POST = "Rez Post";
string L_POST = "Post";
string L_YANK = "Yank";
string LEASH_TO = "LeashTo";

float scanrange = 10.0;
list postbuttons;
list postkeys;
string postprompt;
integer postchannel = 834531;
string menuuser;
integer postlistener;
integer danglecount = -1;
integer menucount = -1;
key leash_holder;

string sensormode;
list leashers;
string tmpname;
key cmdgiver;

list lengths = ["1", "2", "3", "4", "5", "8","10" , "15", "20", "25", "30"];

debug(string str)
{
//llOwnerSay(llGetScriptName() + ": " + str);
}

DeliverObject(key id, string object)
{
string version = "0.0";
string url = "http://collardata.appspot.com/updater/check?";
url += "object=" + llEscapeURL(object);
url += "&version=" + llEscapeURL(version);
llHTTPRequest(url, [HTTP_METHOD, "GET",HTTP_MIMETYPE,"text/plain;charset=utf-8"], "";
llInstantMessage(id, "Queuing delivery of " + object + ". It should be delivered in about 30 seconds.";
}

LeashMenu(key id)
{
currentmenu = "leash";
menuchannel = -(integer)llFrand(999950.0) + 30;
list buttons;
buttons += [LEASH, L_YANK, L_LENGTH];
buttons += [LEASH_TO, UNLEASH, GIVE_HOLDER];
buttons += [L_POST, REZ_POST, GIVE_POST ];
buttons += [STAY, UNSTAY, UPMENU];
buttons = RestackMenu(buttons);
string prompt = "Leash Options";
prompt += "\n(Menu will time out in " + (string)menutimeout + " seconds.)";
menulistener = llListen(menuchannel, "", id, "";
menucount = 45;
llSetTimerEvent(1.0);
llDialog(id, prompt, buttons, menuchannel);
}

LengthMenu(key id)
{
currentmenu = "length";
menuchannel = -(integer)llFrand(999950.0) + 30;
list buttons;
buttons += lengths;
buttons += [UPMENU];
buttons = RestackMenu(FillMenu(buttons));
string prompt = "Set a leash length in meter:";
prompt += "\n(Menu will time out in " + (string)menutimeout + " seconds.)";
menulistener = llListen(menuchannel, "", id, "";
menucount = 45;
llSetTimerEvent(1.0);
llDialog(id, prompt, buttons, menuchannel);
}

LeashToMenu(key id, list leashto)
{
currentmenu = "leashto";
string prompt = "Pick someone to leash to.";
prompt += " (Menu will time out in 45 seconds.)";
if (llGetListLength(leashto) > 11)
{
leashto= llList2List(leashto, 0, 10);
}
list buttons = leashto;//we're limiting this to 11 avs
buttons += [UPMENU];
buttons = RestackMenu(FillMenu(buttons));
menucount = 45;
llSetTimerEvent(1.0);
menuchannel = llRound(llFrand(999999.0)) + 200;
menulistener = llListen(menuchannel, "", id, "";
llDialog(id, prompt, buttons, menuchannel);
}

list FillMenu(list in)
{ //adds empty buttons until the list length is multiple of 3, to max of 12
while (llGetListLength(in) != 3 && llGetListLength(in) != 6 && llGetListLength(in) != 9 && llGetListLength(in) < 12)
{
in += [" "];
}
return in;
}

list RestackMenu(list in)
{ //re-orders a list so dialog buttons start in the top row
list out = llList2List(in, 9, 11);
out += llList2List(in, 6, ;
out += llList2List(in, 3, 5);
out += llList2List(in, 0, 2);
return out;
}

//5000 block is reserved for IM slaves

Popup(key id, string message)
{ //one-way popup message. don't listen for these anywhere
llDialog(id, message, [], 298479);
}

SetTexture(string newtex)
{
part_texture = newtex;
//tell wearer
string message = "Leash texture set to " + part_texture;
if (leasher != NULL_KEY)
llInstantMessage(leasher, message);
llOwnerSay(message);
}

SetLength(float newlength, key id)
{
length = newlength;
// llTarget needs to be changed to the new length
if(!stay)
{
llTargetRemove(targethandle);
targethandle = llTarget(pos, length);
}
//tell wearer
string message = "Leash length set to " + (string)length;
llInstantMessage(id, message);
llOwnerSay(message);
}

LeashTo(key holder, integer rank, list leashpoints)
{
danglecount = -1;
stay = FALSE;
lastrank = rank;

//if more than one leashpoint, listen for all strings, else listen just for that point
string listenfor = "";
integer leashpointcount = llGetListLength(leashpoints);
if (leashpointcount == 1)
{
listenfor = (string)holder + llList2String(leashpoints, 0) + " ok";
}

//only listen for a leash holder if we've been passed at least one leash point
if (leashpointcount)
{
listenhandle = llListen(holderchannel, "", NULL_KEY, listenfor);
}

//set up movement and particle targets.
leasher = holder;
part_target = leasher;//send leash particles to leasher av until we hear from a leash holder prim
LeashParticles(part_target);
// change to llTarget events by Lulu Pink
pos = llList2Vector(llGetObjectDetails(leasher, [OBJECT_POS]), 0);
targethandle = llTarget(pos, length);
llMoveToTarget(pos, 1.0);

//announce to leash holder prims
integer n;
for (n = 0; n < leashpointcount; n++)
{
llSay(holderchannel, (string)holder + llList2String(leashpoints, n));
}
}

StayPut(key id, integer rank)
{
if(leasher != NULL_KEY)
{
llParticleSystem([]);
leasher = NULL_KEY;
}
lastrank = rank;
stay = TRUE;
pos = llGetPos();
llTargetRemove(targethandle);
llMoveToTarget(pos,0.1);
llInstantMessage(id,"You commanded " + llKey2Name(llGetOwner()) + " to stay in place, to allow to move again, either leash the slave with the grab command or use unstay to enable movement again.";
llOwnerSay(llKey2Name(id) + " commanded you to stay in place, you cannot move until the command is revoked again.";
}

Unleash()
{
llStopMoveToTarget();
danglecount = -1;
llListenRemove(listenhandle);
llTargetRemove(targethandle);
llParticleSystem([]);
leasher = NULL_KEY;
}

LeashParticles(key target)
{
debug("sending particles to " + (string)target);
//send stream of particles toward target
string texture = part_texture;
integer flags = 0;
flags = flags | PSYS_PART_EMISSIVE_MASK;
flags = flags | PSYS_PART_FOLLOW_SRC_MASK;
flags = flags | PSYS_PART_FOLLOW_VELOCITY_MASK;
integer pattern = PSYS_SRC_PATTERN_DROP;

if (target != NULL_KEY)
flags = flags | PSYS_PART_TARGET_POS_MASK;

list sys = [
PSYS_PART_MAX_AGE,6.0,
PSYS_PART_START_COLOR, <1,1,1>,
PSYS_PART_END_COLOR, <0,0,1>,
PSYS_PART_START_ALPHA, 1.0,
PSYS_PART_END_ALPHA, 0.5,
PSYS_PART_START_SCALE,<.07,.07,.1>,
PSYS_PART_END_SCALE,<0.1,0.1,0.1>,
PSYS_SRC_BURST_RATE, 0.03,
PSYS_SRC_BURST_PART_COUNT,1,
PSYS_SRC_BURST_RADIUS,0.1,
PSYS_SRC_BURST_SPEED_MIN,1.0,
PSYS_SRC_BURST_SPEED_MAX,1.0,
PSYS_SRC_ACCEL, <0,0,-0.4>,
PSYS_SRC_ANGLE_BEGIN,0.0,
PSYS_SRC_ANGLE_END,PI,
PSYS_SRC_OMEGA, <0,0,1>,
PSYS_SRC_MAX_AGE, 0.0,
PSYS_PART_FLAGS,flags,
PSYS_SRC_PATTERN, pattern,
PSYS_SRC_TARGET_KEY,target,
PSYS_SRC_TEXTURE, texture
];
llParticleSystem(sys);
}

integer isInSim(vector v)
{
if(v == ZERO_VECTOR || v.x < 0 || v.x > 256 || v.y < 0 || v.y > 256)
return FALSE;
else
return TRUE;
}

integer KeyIsAv(key id)
{
return llGetAgentSize(id) != ZERO_VECTOR;
}

integer startswith(string haystack, string needle) // http://wiki.secondlife.com/wiki/llSubStringIndex
{
return llDeleteSubString(haystack, llStringLength(needle), -1) == needle;
}

integer isKey(string id)
{ // verifying the string is a key
list keys = ["0","1","2","3","4","5","6","7","8","9","a","b","c","d","e","f","-"];
if(llStringLength(id) != 36)
{
debug("wrong length";
return FALSE;
}
else if(llGetSubString(id, 8, != "-" || llGetSubString(id, 13, 13) != "-" || llGetSubString(id, 18, 1 != "-" || llGetSubString(id, 23, 23)!= "-" )
{
debug("wrong dashes";
return FALSE;
}
else
{
integer i;
for (i = 0; i < 36; i++)
{
string temp = llGetSubString(id, i, i);
if(llListFindList(keys, [temp]) == -1)
{
debug("wrong char " + temp);
return FALSE;
}
}
return TRUE;
}
}

LeashToHelp(key id)
{
llMessageLinked(LINK_THIS, POPUP_HELP, llKey2Name(llGetOwner()) + " has been leashed to you. Say _PREFIX_unleash to unleash them. Say _PREFIX_giveholder to get a leash holder.", id);
}

YankTo(key id)
{
vector dest = (vector)llList2String(llGetObjectDetails(id, [OBJECT_POS]), 0);
llMoveToTarget(dest, 0.5);
llSleep(2.0);
llStopMoveToTarget();
}

default
{
state_entry()
{
Unleash();
llSleep(1.0);
llMessageLinked(LINK_THIS, MENUNAME_RESPONSE, parentmenu + "|" + submenu, NULL_KEY);
}

on_rez(integer param)
{
llResetScript();
}

link_message(integer sender, integer auth, string str, key id)
{
//only respond to owner, secowner, group, wearer
if (auth >= COMMAND_OWNER && auth <= COMMAND_WEARER)
{
list params = llParseString2List(str, [" "], []);
string command = llList2String(params, 0);
if (str == "grab" || str == "leash"
{
if (leasher != NULL_KEY && auth <= lastrank)
{ //if leashed, only move leash if commander's authority greater than current leasher's
LeashTo(id, auth, ["handle"]);
}
else
{ //if unleashed, then leash if commander authorized, only owner, secowner, and group may "grab"
if (auth >= COMMAND_OWNER && auth <= COMMAND_GROUP)
{
LeashTo(id, auth, ["handle"]);
}
}
}
else if(command == "leashto"
{
tmpname = llList2String(params, 1);
debug("leashing to " + tmpname);
if(isKey(tmpname))
{
list leashpoints = llList2List(params, 2, -1);
debug("leash target is key";//could be a post, or could be we specified an av key
key leashingto = (key)tmpname;
LeashTo(leashingto, auth, leashpoints);

//need to notify target how to unleash. only do if:
//they're an avatar
//they didn't send the command
//they don't own the object that sent the command
if (KeyIsAv(leashingto) && id != leashingto && llGetOwnerKey(id) != leashingto)
{
LeashToHelp(leashingto);
}
}
else
{
debug(tmpname + " isn't key";
sensormode = "chatleashto";
if(llStringLength(tmpname) > 1)
{
llSensor("", "", AGENT, scanrange, PI);
cmdgiver = id;
}
}
}
else if (str == "giveholder"
{
llGiveInventory(id, "Leash Holder";
}
else if (str == "givepost"
{
llGiveInventory(id, "OC_Leash_Post";
}
else if (str == "rezpost"
{
vector position = llGetPos();
rotation angle = llGetRot();
vector posta = <0,90,0>;
posta *= DEG_TO_RAD;
rotation quat = llEuler2Rot(posta);
vector offset = <1.0, 0, 0.5>;

llRezObject( "OC_Leash_Post", position + (offset * angle), ZERO_VECTOR, quat, 0 );
}
else if (str == "unleash"
{ //allow if from leasher or someone outranking them
if (id == leasher || auth <= lastrank)
Unleash();
}
else if (str == "yank" && id == leasher)
{
YankTo(id);
}
else if (llList2String(params, 0) == "length"
{
float newlength = (float)llList2String(params, 1);
if (leasher == NULL_KEY)
{ //if unleashed, any authorized person can change length
SetLength(newlength, id);
}
else if (id == leasher)
{ //leasher can change length
SetLength(newlength, id);
}
else if (auth <= lastrank)
{ //people outranking the leasher can change length
SetLength(newlength, id);
}
}
else if (str == "reset"
{
if (auth == COMMAND_WEARER || auth == COMMAND_OWNER)
{ //only owner and wearer may reset
llResetScript();
}
}
else if (str == "post"
{
if (auth >= COMMAND_OWNER && auth <= COMMAND_GROUP)
{
menuuser = id;
sensormode = "post";
llSensor("", NULL_KEY, SCRIPTED, scanrange, PI);
}
}
else if(command == "post"
{
if (auth <= lastrank || lastrank == 0)
{
//Leash2Post((key)llList2String(params, 1),auth);
LeashTo((key)llList2String(params, 1), auth, []);
}
else
{
string wearer = llKey2Name( llGetOwner() );
string swearer = llList2String( llParseString2List( llKey2Name( llGetOwner() ), [" "], [] ), 0 );
llInstantMessage(id, "Sorry, someone who outranks you on " + wearer +"'s collar leashed " + swearer + " already.";
}
}
else if (str == "stay"
{
if (auth >= COMMAND_OWNER && auth <= COMMAND_GROUP)
// if ((id != llGetOwner()) && (auth >= COMMAND_OWNER && auth <= COMMAND_GROUP))
StayPut(id, auth);
}
else if ((str == "unstay" || str == "move" && stay)
{
if (auth <= lastrank)
{
stay = FALSE;
llOwnerSay("You are free to move again.";
llStopMoveToTarget();
}
}
else if (llGetInventoryType(str) == INVENTORY_TEXTURE)
{ //use the new texture. check hierarchy though
if (leasher == NULL_KEY)
{ //if unleashed, then any authorized person can changed texture, including wearer
SetTexture(str);
}
else if (id == leasher)
{ //leasher can change texture
SetTexture(str);
LeashParticles(part_target);
}
else if (auth < lastrank)
{ //people outranking the leasher can change texture
SetTexture(str);
LeashParticles(part_target);
}
}
}
else if (auth == COMMAND_EVERYONE)
{
if (id == leasher)
{
if (str == "unleash"
{
//TODO: implement this for secowners and group members too if they get leashed to
Unleash();
}
else if (str == "giveholder"
{
llGiveInventory(id, "Leash Holder";
}
else if (str == "yank"
{
YankTo(id);
}
}
}
else if (auth == MENUNAME_REQUEST)
{
llMessageLinked(LINK_THIS, MENUNAME_RESPONSE, parentmenu + "|" + submenu, NULL_KEY);
}
else if (auth == SUBMENU && str == UPMENU)
{
llMessageLinked(LINK_THIS, MENUNAME_RESPONSE, parentmenu + "|" + submenu, NULL_KEY);
}
else if (auth == SUBMENU && str == submenu)
{
LeashMenu(id);
}
else if (auth == COMMAND_SAFEWORD)
{
stay = FALSE;
Unleash();
}
}

sensor(integer num)
{
//give menuuser a list of things to choose from, loop the list off at 12 so we don't need multipage menu
if (num > 12)
{
num = 12;
}
if (sensormode == "menuleashto"
{
leashers = [];
list avs;//just used for menu building
integer n;
for (n = 0; n < num; n++)
{
leashers += [llDetectedKey(n), llDetectedName(n)];
avs += [llDetectedName(n)];
}
LeashToMenu(menuuser, avs);
}
else if (sensormode == "chatleashto"
{ //loop through detected avs, seeing if one matches tmpname
integer n;
for (n = 0; n < num; n++)
{
string name = llDetectedName(n);
if (startswith(llToLower(name), llToLower(tmpname)))
{
leasher = llDetectedKey(n);
LeashTo(leasher, lastrank, ["handle", "collar"]);
//need to notify target how to unleash. only do if:
//they're an avatar
//they didn't send the command
//they don't own the object that sent the command
if (KeyIsAv(leasher) && cmdgiver != leasher && llGetOwnerKey(cmdgiver) != leasher)
{
LeashToHelp(leasher);
}
return;
}
}
//if we got to this point, then no one matched
llInstantMessage(cmdgiver, "Could not find '" + tmpname + "' to leash to.";
}
else if(sensormode == "post"
{
postbuttons = [];
postprompt = "Pick the object on which you want the sub to be leashed to. If it's not in the list, have the sub move closer and try again.\n";
postkeys = [];
integer n;
for (n = 0; n < num; n ++)
{
string name = llDetectedName(n);
if(name != "Object"
{
postbuttons += [(string)(n + 1)];
if (llStringLength(name) > 44)
{ //added to prevent errors due to 512 char limit in poup prompt text
name = llGetSubString(name, 0, 40) + "...";
}
postprompt += "\n" + (string)(n + 1) + " - " + name;
postkeys += [llDetectedKey(n)];
}
}
//prompt can only have 512 chars
while (llStringLength(postprompt) >= 512)
{ //pop the last item off the buttons, keys, and prompt
postbuttons = llDeleteSubList(postbuttons, -1, -1);
postkeys = llDeleteSubList(postkeys, -1, -1);
postprompt = llDumpList2String(llDeleteSubList(llParseString2List(postprompt, ["\n"], []), -1, -1), "\n";
}
postbuttons = RestackMenu(FillMenu(postbuttons));
menuchannel = -(integer)llFrand(999950.0) + 30;
postlistener = llListen(menuchannel, "", menuuser, "";
menucount = 60;
llSetTimerEvent(1.0);
currentmenu = "post";
llDialog(menuuser, postprompt, postbuttons, menuchannel);
}
}

no_sensor()
{ //nothing close by to leash on, tell menuuser
llInstantMessage(menuuser, "Unable to find targets to leash to.";
}
at_target(integer num, vector position, vector ourpos)
{
llStopMoveToTarget();
llTargetRemove(targethandle);
pos = llList2Vector(llGetObjectDetails(leasher,[OBJECT_POS]),0);
targethandle = llTarget(pos, length);
if(leasher != part_target)
{
if(llKey2Name(part_target) == ""
{
part_target = leasher;
LeashParticles(part_target);
}
}
else if(llKey2Name(leash_holder) != ""
{
part_target = leash_holder;
LeashParticles(part_target);
}
}
timer()
{
if(leasher != NULL_KEY)
{
vector newpos = llList2Vector(llGetObjectDetails(leasher,[OBJECT_POS]),0);
//if the leasher is gone we remove the target
if(!isInSim(newpos) && danglecount == -1)
{
llTargetRemove(targethandle);
llParticleSystem([]);
llListenRemove(listenhandle);
danglecount = 120;
}
else if(isInSim(newpos) && danglecount != -1)
{
LeashParticles(part_target);
llTargetRemove(targethandle);
targethandle = llTarget(newpos, length);
llMoveToTarget(newpos, 1.0);
danglecount = -1;
}
}
if((!menucount && !danglecount) || (!menucount && danglecount == -1) || (menucount == -1 && !danglecount))
{
llSetTimerEvent(0.0);
}
if(!danglecount)
{
danglecount = -1;
}
else if(danglecount > 0)
danglecount--;
if(!menucount)
{
menucount = -1;
llListenRemove(menulistener);
}
else if(menucount > 0)
menucount--;
}
not_at_target()
{
if(stay)
{
llMoveToTarget(pos,0.1);
}
else
{
vector newpos;
newpos = llList2Vector(llGetObjectDetails(leasher,[OBJECT_POS]),0);
if (pos != newpos)
{
pos = newpos;
llTargetRemove(targethandle);
targethandle = llTarget(pos, length);
}
llMoveToTarget(pos,0.7);
//if the leasher is gone we remove the target and stop following
if(!isInSim(newpos) && danglecount == -1)
{
llStopMoveToTarget();
llTargetRemove(targethandle);
danglecount = 120;
llParticleSystem([]);
llSetTimerEvent(1.0);
}
if(leasher != part_target)
{
if(llKey2Name(part_target) == ""
{
part_target = leasher;
LeashParticles(part_target);
}
}
else if(llKey2Name(leash_holder) != ""
{
part_target = leash_holder;
LeashParticles(part_target);
}
}
}
changed(integer change)
{
if(change & CHANGED_TELEPORT)
{
if(leasher != NULL_KEY)
{ //wait a moment after teleporting...
llSleep(3.0);
vector newpos;
newpos = llList2Vector(llGetObjectDetails(leasher,[OBJECT_POS]),0);
if(newpos != ZERO_VECTOR)
{
LeashParticles(part_target);
llTargetRemove(targethandle);
targethandle = llTarget(pos, length);
}
}
}
}
//##########################################################
listen(integer channel, string name, key id, string message)
{
if(channel == holderchannel)
{ //we heard from a leash holder. re-direct particles
if (llGetOwnerKey(id) == leasher)
{
leash_holder = id;
part_target = id;
LeashParticles(part_target);
}
}
else if(channel == menuchannel)
{
llListenRemove(menulistener);
menuuser = id;
if(message == L_LENGTH)
{
LengthMenu(id);
}
else if(message == UPMENU)
{
if(currentmenu == "length"
{
LeashMenu(id);
}
else
{
llMessageLinked(LINK_THIS, SUBMENU, parentmenu, id);
}
}
else if(message == LEASH_TO)
{
sensormode = "menuleashto";
llSensor("", "", AGENT, scanrange, PI);
}
else if(currentmenu == "leashto"
{
integer index = llListFindList(leashers, [message]);
if (index != -1)
{
// llMessageLinked(LINK_THIS, COMMAND_NOAUTH, "leashto " + llList2String(leashers, index -1), id);
leasher = (key)llList2String(leashers, index -1);
LeashTo(leasher, lastrank, ["handle", "collar"]);


if (id != leasher)
{
LeashToHelp(leasher);
}
}
}
else if(currentmenu == "post"
{
integer postnum = (integer)message - 1;
llMessageLinked(LINK_THIS, COMMAND_NOAUTH, "post " + llList2String(postkeys, postnum), id);
}
else if(message == GIVE_HOLDER)
{
llMessageLinked(LINK_THIS, COMMAND_NOAUTH, "giveholder", id);
LeashMenu(id);
}
else if(message == GIVE_POST)
{
llMessageLinked(LINK_THIS, COMMAND_NOAUTH, "givepost", id);
LeashMenu(id);
}
else if(message == REZ_POST)
{
llMessageLinked(LINK_THIS, COMMAND_NOAUTH, "rezpost", id);
LeashMenu(id);
}
else if(llListFindList(lengths,[message]) != -1)
{
llMessageLinked(LINK_THIS, COMMAND_NOAUTH, "length " + message, id);
LeashMenu(id);
}
else
{
llMessageLinked(LINK_THIS, COMMAND_NOAUTH, llToLower(message), id);
}
menucount = -1;
}
}
}

I find the OpenCollar scripts pretty baffling, too, because whenever anything interesting happens it usually seems to involve several different scripts doing bits and pieces and sending link messages to each other to say what's going on, so it's a bit of problem trying to get the full picture.

else if (llGetInventoryType(str) == INVENTORY_TEXTURE)
                  {   //use the new texture.  check hierarchy though
                      if (leasher == NULL_KEY)
                      {    //if unleashed, then any authorized person can changed texture, including wearer
                          SetTexture(str);
                      }
                      else if (id == leasher)
                      {   //leasher can change texture
                          SetTexture(str);
                          LeashParticles(part_target);
                      }
                      else if (auth < lastrank)
                      {   //people outranking the leasher can change texture
                          SetTexture(str);
                          LeashParticles(part_target);
                      }

is presumably how you change the chain's texture, but since the string -- which must be the name of a texture in the collar's inventory -- comes from a link message, your guess about which of the many scripts in that collar is generating the list of textures and -- I assume -- using it to populate a menu and then sending a link message to this script to say which texture has been chosen, is as good as anyone's.

I've found the OpenCollar developers very helpful and willing to talk about how the thing works. Maybe contacting them to ask them to explain the scripts a bit might be a plan?