Good luck! Some mail-order companies (Freestyle, PhotoWarehouse, etc) that cut down rolls of film from the film manufacturers used their own generic markings for the sheets. Those markings reminds me of some of that from way back.
Just checked some of my 8x10 negatives -- I have a 8x10 neg on Freestyle Arista 125 that have the identical notches as your mystery film. Negative was exposed in 2005, so film predates that by a bit. (edited: I just found some neg exposed in 2001 on Arista 125). Like fine red wine, my film tends to be aged. It is re-branded Ilford FP4.
But as I wrote, those notches are probably not unique to Arista 125, so yours might be something different. My actual Ilford-boxed FP4+ from the 1990s had two "U" shaped notches, but they are spaced significantly farther apart than your example. (Newer FP4+ film is now notched differently).