Code to save previous selected value in form in MSD Axapta

Declare variable in class declaration

 #define.CurrentVersion(1)  
   #localmacro.CurrentList  
     _itmeid, _description, _classtype  
   #endmacr  
 define pack method  
 public container pack()  
 {  
   return [#CurrentVersion,#CurrentList];  
 }  
 Then define unpack method  
 public boolean unpack(container _packedClass)  
 {  
   Version version = conpeek(_packedClass,1);  
   ;  
   switch (version)  
   {  
     case #CurrentVersion :  
       [version, #CurrentList] = _packedClass;  
     break;  
     default :  
       return false;  
   }  
   return true;  
 }