Unknown Brackets on Beater Box

At some stage in the past someone has screwed three L shaped brackets to the bottom of the flying shuttle beater box at each end so that one arm of the bracket sticks up vertically in front of the box with gap between the bracket and the front of the box of about half an inch. I presume that they are later aditions as I can see no reference to them in the Leclerc documentation.
They look as if they are designed to hold something that slots into the gap. I don't want to remove them if they could prove useful.