channels 230 232 will then overlie one another and cord continuous loop operator 154 is pulled into the then overlying one way channels 230 232 as depicted in fig1 cord continuous loop operator 154 is pulled further and completely into apertures 222 224 with projections 234 236 angling into apertures 222 224 and the inner ends of one way channels 230 232 being narrower than the diameter of cord continuous loop operator 154 the cord is held securely in apertures 222 224 and cannot pass back easily through one way channels 230 232 with hold down device 200 installed on cord continuous loop operator 154 and inward pressure against arms 202 204 subsequently being released cord continuous loop operator 154 angles between the then misaligned apertures 222 224 and against serrated portions 226 228 serrated portions 226 228 engage and embed into cord continuous loop operator 154 such that hold down device 200 is held securely at its position along the length of cord continuous loop operator 154 hold down device 200 securely engages cord continuous loop operator 154 and is not easily dislodged there from hold down device 200 renders the window covering inoperable in that the continuous loop operator 154 can be advanced only until hold down device 200 encounters head rail 152 hold down device 200 is mounted in its final position within window covering installation 150 after head rail 152 is installed in the window opening arms 202 204 are urged toward one another so that mounting blocks 208 210 engage.