Abstract: A hydraulic system, comprising a housing (1) on which a first and second connecting member (30,50) are fitted, for connecting the first and the second line respectively The first and the second line are provided with a first and a second insertion fitting (20,40) respectively, each connecting member (30,50) having a body (31,51) with an insertion bore (32,52) for an insertion fitting (20,40), which insertion bore (32,52) extends from an insertion side, and each connecting member (30,50) further comprising an elastic locking member (35,55). The part of the insertion bore (32,52) of each connecting member (30,50) extending between the insertion side and the locking member (35,55) forms a coding part (37,57), in which the coding part (37) of the first connecting member (30) differs with regard to one or more dimensions thereof from the coding part (57) of the second connecting member (50).