Is this hole supposed to be there? (W123 under battery tray)

[BenA105]

Hey folks,

I've been interior leak hunting on my '82 W123 wagon and I currently have the battery tray out of the car. I'm cleaning it up and giving it a coat of POR15/Miracle Paint to preserve it. As well as that, I've been trying to see if there's leaks coming into the cabin from underneath. I do get that dreaded wet floor on the passenger side of the car. I also live in Vancouver, BC, so we get a fair amount of rain!

So my question: is this hole a drainage hole, or is this a nicely rounded rust hole? Pic attached:





I'm not convinced it is a rust hole. It's basically perfect. I don't want to fix it if it doesn't need fixing!

Thanks!