One of the early sins of office file formats, translating formula symbols not just in presentation but right down in the persistent form. If memory serves me r

One of the early sins of office file formats, translating formula symbols not just in presentation but right down in the persistent form. If memory serves me right, back when MS Office macro viruses were the threat du jour, there was already a bit of a remedy in place for those formats that would translate the formulas and macros of incoming files from a different language version of the same software. This caused secondary waves of "mutated" viruses that had crossed multiple language barriers and came back slightly different but still working, foiling the efforts of checksum based virus scanners.