A marker-holder system for an electrical terminal block comprising a longitudinal marker-holder device according to a direction of extension, with a first end in the direction of extension and a second end in the direction opposite to the direction of extension, the system comprising a first fastener configured to be disposed on the terminal block, the first end and/or the second end being configured to cooperate with the first fastener in a removable manner and according to a rotary connection, between a first position in which a first face of the marker-holder device is oriented towards the terminal block and a second face of the marker-holder device is oriented in a direction opposite to the terminal block, and a second position in which the first face of the marker-holder device is oriented in a direction opposite to the terminal block and the second face of the marker-holder device is oriented towards the terminal block.