100 Lire Istituto Bancario San Paolo di Torino

San Paolo di Torino was one of a handful of Italian istituti di credito di diritto pubblico authorized to issue assegni circolari — essentially guaranteed bank drafts functioning as near-currency — rather than banknotes in the strict central-bank sense. The 100 Lire denomination existed because Italy suffered a chronic small-coin shortage through the 1970s, and these instruments plugged the gap that the Zecca couldn't fill fast enough in metal.

The watermark is the primary security feature precisely because these circulated at par with state-issued currency and needed at least minimal protection against reproduction. Counterfeiting small-denomination commercial paper was a genuine problem during this period.