(EN) A security thread (2), for identification of security documents such as banknotes, has a magnetic layer (4) sandwiched between polymeric layers (6, 8), where one of the layers (8) is a piezoelectric layer such as PVDF. The piezoelectric layer (8) may be poled intermittently such the piezoelectric layer is coded. A particularly compact security thread with enhanced multiple coded features is thus provided.
