RTC javascript dojo

Hi,
I have a RTC javascript code that set Timestamp Custome attributes. What is the dojo.require("com.ibm.team.workitem.shared.common.BigDecimal"); istruction that I have on the script (other people wrote the script and I'm analyzing the script.
thanks in advance for help !

here an extract of the code :

/*******************************************************************************
 * Licensed Materials - Property of IBM
 * (c) Copyright IBM Corporation 2011. All Rights Reserved.
 *
 * Note to U.S. Government Users Restricted Rights: 
 * Use, duplication or disclosure restricted by GSA ADP Schedule
 * Contract with IBM Corp.
 *******************************************************************************/
dojo.provide("com.ibm.example.workitems.providers.setDate");

dojo.require("com.ibm.team.workitem.api.common.WorkItemAttributes");
dojo.require("dojo.date");
dojo.require("dojo.date.stamp");
dojo.require("com.ibm.team.workitem.shared.common.BigDecimal");

(function() {
    var doDebug = false;
    var scriptname = "setDate";
   
    var WorkItemAttributes= com.ibm.team.workitem.api.common.WorkItemAttributes;
    dojo.declare("com.ibm.example.workitems.providers.setDate", null, {

        getValue: function(attributeId, workItem, configuration) {
        var wiType = workItem.getValue(WorkItemAttributes.TYPE);
       
       
        if ((wiType=="defect")||(wiType=="enhancement"))
        {
            debug("This is a defect...");
            debug("Processing attributes for automatic values changes...");
 
            var currentState = workItem.getValue(WorkItemAttributes.STATE);
            var currentAttributeValue = workItem.getValue(attributeId);
            var currentDate = new Date();
           
       
           
            if (attributeId == "com.ibm.team.custom.acg.L3closingdateD")
            {
              // Processing L3_ClosingDate
              debug("Processing L3_ClosingDate...");             

              var L3_ClosingDate=dojo.date.stamp.fromISOString(workItem.getValue('com.ibm.team.custom.acg.L3closingdateD'));
              var L3_SpecialistLabel=workItem.getLabel("l3");
              var resolution=workItem.getValue(WorkItemAttributes.RESOLUTION);
             
            
                          
             
            
              // if ((state= Fixed) && (L3Specialist!=Unassigned) && (L3_Close_date==null)
              // then L3_Close_date=date
              if ((currentState == "acg.ticketWorkflow.state.s10") && ((L3_SpecialistLabel!="") && (L3_SpecialistLabel!="Unassigned")) && (L3_ClosingDate==null))
              {
                debug("State=Fixed, L3Specialist=Assigned, L3_ClosingDate=Unassigned ---> Setting L3_ClosingDate to current date");
                return dojo.date.stamp.toISOString(currentDate, {milliseconds:true, zulu:true});
              }
                           
      .............
 .........................................
.....

Many thanks!