Systems and methods are described herein for embedding and detecting a watermark in a digital content file, such as an audio file or a video file. The frame can by its modular construction be adapted to an arbitrary number of shielding or cover plates that are comprised in such cards and are placed or are to be placed in the opening. The asymmetric synthesis method employs the catalyst. The metallic spring system is operable to compress in response to relative movement between the connection body and the connection element.