I am not actually sure if these are the initials NBFS.
Something tells me it is not as simple as that . First there is the dash under what looks like a 'B' but then it might not be a 'B' at all. Then there's that apostrophe between the 'F' and the 'S'. These two at least I am sure about.
So perhaps it is a tag of ownership, NBF's or perhaps I am reading way too much into some big splotches of colour on an abandoned gypsum loading facility.
What ever it means, it's colourful and I liked it.
Photo: Robert Rath, ‘Day 617, NBFS' 1/160s f/8.0 ISO100 15mm