suppose to have typedef struct { struct { u16_t ff1; u16_t ff2; u16_t ff3; } f1[3]; u8_t f2; u8_t f3; u8_t f4; u16_t f5; } Param_t; I need to know the offset of the fields. For example f1[0].ff1 is placed at the offset 0, and f1[2].ff2, or f3? There is a way to obtain these offsets without have an istance of Param_t? thanks -- Massimiliano Cialdi cialdi@xxxxxxxxxxx m.cialdi@xxxxxxxx