Iranian 5 Rial fractured die

I have an Iranian 5 rial coin (KM-1176), 1977 (MS2536), with a very obvious 3 way die fracture.  A pronounced ridge extending from center out 3 ways, on both sides of the coin.  I didn't see any mention of this in the catalog.  Anyone hear of this before?

Thanks for the help,

Raider