Abstract: The invention relates to a construction-kit system comprising at least one primary-valve block (10), provided with at least two groups of connection lines (12, 14), which are all interconnected at one point (16) via a connection line of one of the groups (12) to form a fluidic connection. At least two additional connection lines of said group (12) are respectively connected to a corresponding connection line of the other group (14). According to the invention, at least three dummy components (18) are connected in the connection lines of the other group (14) for the insertion of predetermined valve components and at least two additional dummy components (20) are connected between a common connection line (14a) of the other group (14) and an additional respective corresponding connection line (14b) of said other group (14).