100 Piso Seal type 5, Without security thread

The absence of a security thread on these notes reflects a transitional gap in the BSP's production capability during the late 1990s — the Security Plant Complex in Quezon City had not yet fully standardized thread insertion across all denominations before the series was phased out. The overlapping signature combinations across 1998 alone, spanning the end of Ramos's presidency and the opening months of Estrada's, compressed into a single print year, is unusual even by Philippine standards of frequent signature turnover.

The shift from red to black serial numbers within the Estrada-Singson pairing is a minor but real production distinction that affects collector sorting more than value.