Create multi select option set in dynamics crm 2011

The following function is used to add multi select optionset in CRM 2011.

For this,we need to create two fields.
 1. new_optionset (type : Optionset)
 2. new_text (type : multi line text) - This is hidden field.

Here , we have to pass 5 parameters in MultiPickList function.

param1- Optionset field Name (new_optionset)
param2 - Multiline text field (new_text)
param3 - empty string ("")
param4 - selected color ( I used green).



function MultiPickList(param1, param2, param3, param4, param5) {
    try {
        var fn = arguments.callee.toString().match(/function\s+([^\s\(]+)/);
        if (param1 == null || param2 == null) {
            alert("Error: Parameter missing. \n Format: <optionset fieldsname> ,  <option value text field> ,  [<option header>], [<select color>]   , [<deselect color>] ,  \n [" + "Function=" + fn[1] + "]");
            return true;
        }
        var tparamtype = Xrm.Page.data.entity.attributes.get(param1).getAttributeType();
        if (tparamtype != "optionset") {
            alert(param1 + "(first parameter) should be of type optionset \n" + "[function=" + fn[1] + "]");
            return true;
        }
        var tparamtype = Xrm.Page.data.entity.attributes.get(param2).getAttributeType();
        if (tparamtype != "memo") {
            alert(param2 + "(second parameter) should be of type memo (text with mutiline) \n[function=" + fn[1] + "]");
            return true;
        }
        var plOptions = param1;
        var plText = param2;
        var plMenuItem = "View Selected List";
        var SelectedList_orig = crmForm.all[plText];
        var FullList = crmForm.all[plOptions];
        var SelCtr = -1;
        var new_selColor = "orange";
        var new_deSelColor = "white";
        if (param4 != null)
            new_selColor = param4;
        if (param5 != null)
            new_deSelColor = param5;
        var SelectedList = SelectedList_orig.value.split("\r\n");
       
        crmForm.all[plText].style.display = "none";
        if (FullList != null && SelectedList != null) {
            initColor();
            if (param3 != null && param3 != "") {
                plMenuItem = param3;
            }
            else {
                plMenuItem = FullList.options[0].text;
                changeColor("grey", 0);
            }
           
            for (var ctr = 0; ctr < SelectedList.length; ctr++) {
                selCtr = SelectedIndex(SelectedList[ctr]);
                if (selCtr > -1) {
                    changeColor(new_selColor, selCtr);
                }
            }
        }
        function SelectedIndex(selectedText) {
            var FullListValue;
            for (var ctr1 = 0; ctr1 < FullList.options.length; ctr1++) {
                FullListValue = FullList.options[ctr1].index;
                if (FullListValue == selectedText) {
                    return ctr1;
                }
            }
            return -2;
        }
        crmForm.all[plOptions].attachEvent('onchange', OnChangePL);
        function OnChangePL() {
            var SelCtr = -1;
            var optionSetCntrl = document.getElementById(plOptions);
            var sel = optionSetCntrl.value;
            if (sel == plMenuItem)
                return;
            SelCtr = SelectedIndex(sel);
            var SelColor = "grey";
            SelColor = crmForm.all[plOptions][SelCtr].style.backgroundColor;
            if (SelColor == new_selColor) {
                changeColor(new_deSelColor, SelCtr);
                saveChanges(sel, selCtr, "del");
            }
            else {
                changeColor(new_selColor, SelCtr);
                saveChanges(sel, selCtr, "add");
            }
        }
        function saveChanges(p_selText, p_SelCtr, p_mode) {
            switch (p_mode) {
                case "add":
                    SelectedList.push(p_selText);
                    break;
                case "del":
                    for (var ctr2 = 0; ctr2 < SelectedList.length; ctr2++) {
                        if (SelectedList[ctr2] == p_selText) {
                            SelectedList.splice(ctr2, 1);
                            break;
                        }
                    }
                    break;
            }
            Xrm.Page.getAttribute(plText).setValue(SelectedList.join("\r\n"));
        }
        function initColor() {
            for (var ctr3 = 0; ctr3 < FullList.options.length; ctr3++)
            { changeColor(new_deSelColor, ctr3); }
        }
        function changeColor(newColor, newCtr) {
            crmForm.all[plOptions][newCtr].style.backgroundColor = newColor;
        }
    }
    catch (e)
         { alert(e.description); }
}