Sorry for spamming this forum with three posts, but another unidentified error coin. This one is a 1990 Belgian franc with a strange curved top on the "I" of "BOUDEWIJN I" on the obverse. There is nothing in that position on the reverse that could have left clash marks, and it seems like a very strange shape for a die chip. Possibly the beginning of a small cud that hasn't fully detached yet? This explanation isn't 100% satisfying to me, because the base of the "I" also appears to have a narrow elongation on it, but not a curved one like the "horned" top of the "I."