the remainder of the post 6 along the weakened zone more particularly the tab 20 is in the form of a vertical strip 21 that is adapted to lift clear of the front face 5 the separation between the tab 20 and the post 3 propagates from an upper section 22 of the post 3 toward a lower section 23 as the post 3 deflects downward the tab 20 is designed to shear away from the post 3 upon further deflection of the post 3 fig4 and 5 show alternative examples of weakened zones 16 that are intended to facilitate release of the fastener 11 from the aperture 13 as opposed to the creation of a tab in fig4 the weakened zone 16 is in the form of slots 24 arranged in a cross configuration in fig5 the slots 25 are arranged in a square array around the connection region 15 fig6 and 7 illustrate further examples of the weakened zone 16 being in the form of a u shape slot 26 with fig6 showing an inverted u shape in both cases the weakened zone 16 will result in the creation of a tab 20 fig8 and 9 show the aperture 13 as a rectangular slot 27 and the weakened zone 16 is then formed by horizontal slots 28 in communication with the aperture 13 whereby the overall zone 16 has an i shape or d shape.