5 Piastres Mule error issue

The "mule" designation here refers to a mismatched pairing of printing elements — obverse and reverse plates drawn from different series or printings combined in a single production run, an error that slipped through quality control at the Postal Printing House. Mule errors from Egyptian small-denomination notes of this period are genuinely uncommon in collector literature, partly because the notes circulated heavily at face value and survivors in any condition are underrepresented in Western collections.

Salah Hamad signed across multiple Egyptian Ministry of Finance issues of the 1990s, so the signature alone does little to narrow provenance — the mule pairing is the only meaningful diagnostic here.