multi selection records in form through action type menuitem

create action menu item and add the object name as below class name"multiselectRecords"
add that menuitem in action pane and give the datasource as our datasource (Ex:prodtable)

class multiselectRecords
{
}

public static void main(Args _args)
{
    ProdTable prodtable;

    MultiSelectionHelper selection = MultiSelectionHelper::createFromCaller(_args.caller());

   prodtable = selection.getFirst();

    while (prodtable)

    {

    info(prodtable.ProdId);


        //need to do what ever lkogic here
    prodtable = selection.getNext();

    }
}