Drain holes at the rear of the sills on the A208 chassis. CLK A208

[Martin1999]

Rust checking abd cleaning Mercedes CLK A208. Now I have an apparent rust hole on either side at the back of the sills having removed the ABS plastic over sill. The first conclusion was that these were rust holes but having cleaned them up I am now thinking they may be a rusted drain holes?? so welding them up or blocking them with tiger seal, may not be a good idea. Any knowledge would be greatly appreciated. Thanks in advance