load(
  /*ri!exchanges = values that would come from your checkboxField*/
  
  /*If you stored your exchanges in a constant*/
  local!exchangeConstant:{"CMEEL", "CMECE", "CBOT", "OTHER"},
  
  /*Pull the index position of your exchange choices*/
  local!exchangeIndexes:wherecontains(ri!exchanges, local!exchangeConstant),
  
  /*What classes each exchange currently have*/
  local!classes:
  {
    "Agricultural, Energy, Foreign Exchange",  /* CMEEL */
    "Agricultural, Energy, Foreign Exchange",  /* CMECE */
    "Agricultural, Energy, Foreign Exchange",  /* CBOT */
    "Agricultural, Equity, Interest Rates"     /* OTHER */
  }, 

  /*Pulls which rows of classes to retrieve based on Exchange Indexes*/
  local!classIndexes:apply(
    index(local!classes, _, {}), 
    {local!exchangeIndexes}
    ), 
  
  /*Splits result from local!classIndexes into multiple text values (for checkbox purposes) */  
  local!splitIndexes:split(local!classIndexes, ","), 
  
  /*Removes duplicates*/
  local!removedDuplicates:union(local!splitIndexes, local!splitIndexes), 
  
  local!removedDuplicates
    
)