A connector system comprising: a connector element (17, 31); at least a first structural element and a second structural element, each structural element having a first edge and a second opposite edge, and a corresponding mating groove (25, 26, 39, 40) that is formed in the structural elements extending from the first edge toward the second edge; the connector element (17, 31) comprising a base plate (20, 32) with split-tongue elements (18, 19, 33, 36) protruding from said base plate (20, 32), each split-tongue element (18, 19, 33, 36) designed to mate with one of said mating grooves (25, 26, 39, 40) and having two flexible arms (21, 22, 23, 24, 34, 35, 37, 38) protruding from said base plate (20, 32); said flexible arms (21, 22, 23, 24, 34, 35, 37, 38) having outward facing protruding nubs (41, 42, 43, 44, 98, 99, 100, 101) at their distal ends; each mating groove (25, 26, 39, 40) comprising five regions arranged sequentially from the first edge toward the second edge: a recess region for receiving the base plate (20, 32) of the connector element (17, 31) when the connector element (17, 31) is inserted into the respective groove (25, 26, 39, 40), a converging entry region having sidewalls (49, 50) that converge toward one another, each side wall having an end, a minimum groove width apex region (51, 52) at the ends of the converging sidewalls (49, 50), a diverging hold region having sidewalls (53, 54) extending away from one another, and a cap or termination region; characterized in that: said diverging hold region and said flexible arms (21, 22, 23, 24, 34, 35, 37, 38) and said nubs (41, 42, 43, 44, 98, 99, 100, 101) are disposed such that contact of the nubs (41, 42, 43, 44, 98, 99, 100, 101) with said groove diverging region imposes significant residual arm deflection after the connector element (17, 31) is fully inserted in the mating groove (25, 26, 39, 40) such that a force applied to the diverging hold region by said deflection of the flexible arms (41, 42, 43, 44, 98, 99, 100, 101) as a result of the contact between said nubs (41, 42, 43, 44, 98, 99, 100, 101) and said diverging hold region results in a force component tending to pull said connector split-tongue elements (18, 19, 33, 36) into said mating groove (25, 26, 39, 40). a connector element (17, 31); at least a first structural element and a second structural element, each structural element having a first edge and a second opposite edge, and a corresponding mating groove (25, 26, 39, 40) that is formed in the structural elements extending from the first edge toward the second edge; the connector element (17, 31) comprising a base plate (20, 32) with split-tongue elements (18, 19, 33, 36) protruding from said base plate (20, 32), each split-tongue element (18, 19, 33, 36) designed to mate with one of said mating grooves (25, 26, 39, 40) and having two flexible arms (21, 22, 23, 24, 34, 35, 37, 38) protruding from said base plate (20, 32); said flexible arms (21, 22, 23, 24, 34, 35, 37, 38) having outward facing protruding nubs (41, 42, 43, 44, 98, 99, 100, 101) at their distal ends; each mating groove (25, 26, 39, 40) comprising five regions arranged sequentially from the first edge toward the second edge: a recess region for receiving the base plate (20, 32) of the connector element (17, 31) when the connector element (17, 31) is inserted into the respective groove (25, 26, 39, 40), a converging entry region having sidewalls (49, 50) that converge toward one another, each side wall having an end, a minimum groove width apex region (51, 52) at the ends of the converging sidewalls (49, 50), a diverging hold region having sidewalls (53, 54) extending away from one another, and a cap or termination region; a recess region for receiving the base plate (20, 32) of the connector element (17, 31) when the connector element (17, 31) is inserted into the respective groove (25, 26, 39, 40), a converging entry region having sidewalls (49, 50) that converge toward one another, each side wall having an end, a minimum groove width apex region (51, 52) at the ends of the converging sidewalls (49, 50), a diverging hold region having sidewalls (53, 54) extending away from one another, and a cap or termination region; characterized in that: said diverging hold region and said flexible arms (21, 22, 23, 24, 34, 35, 37, 38) and said nubs (41, 42, 43, 44, 98, 99, 100, 101) are disposed such that contact of the nubs (41, 42, 43, 44, 98, 99, 100, 101) with said groove diverging region imposes significant residual arm deflection after the connector element (17, 31) is fully inserted in the mating groove (25, 26, 39, 40) such that a force applied to the diverging hold region by said deflection of the flexible arms (41, 42, 43, 44, 98, 99, 100, 101) as a result of the contact between said nubs (41, 42, 43, 44, 98, 99, 100, 101) and said diverging hold region results in a force component tending to pull said connector split-tongue elements (18, 19, 33, 36) into said mating groove (25, 26, 39, 40).