I got a pair of Carhart coveralls from Canada a few years ago and they have a small fertical buttton slit on the pocket on the chest.
I was told that welders do something with it but I can't work out what.

Can anyone tell me?

Not hunting related, but I do use them for hunting a fair bit.

Try your Zippo!

Not sure what the slit is for, but I would guess it's for holding something. For example, I used the hammer loop on the leg for holding my torch striker when I was in construction. You might try the carhart website.

Just checked mine, ....no vertical slit but there is a horizontal slit, like a button hole, .......and that's for the carpenter's pencil! A welder might use it for his chalk?
~Arctic~

ON mine, the cut is where I attach the watch chain for the pocket watch,,,,

Aussie,

You've got quality, you've got taste and it's noted. Starched (heavy starch) and pressed is best. No welding slag can cling to it. If slag falls inside, well, you're f'd either way but you will be well dressed for the after and the repair. Most likely to your cods.

Now, to the pocket, thingie. Get the lassies to search all caverns of Carhartts and you'll both be pleased, at least you will be.

Cheers, Mate and tell the dagos howdy for us all.

DB