Contains the size of the bet inserted by the user from the Back betting frame. The Back betting frame is available to the user only if the xml property "show_input_back" of the strategy tag is equal to "y". The Back betting frame is opened when the user clicks on a cell of the "Back" column.
Example: <place condition="@is_horse_selected=1" price="@input_back_price" size="@input_back_size" />
When the horse is checked, place a bet with the inserted size and price.