Zoll Hemdbluse or generic work shirt?

[Mõmmi]

Hi there,

could anyone identify this mysterious blue shirt?
I personally believe it to be a mid-70's Zoll Hemdbluse.





Thanks!

[uscob]

Would be interesting. I also have some (somewhere) but never found out. If it had golden Buttons it would be Reichsbahn, but with silver?