as to leave a web 25 29 33 and 37 bridging the opposing sides of the respective cut a vertical cut 27 31 35 and 39 is then made in the railings 20 to leave the respective web 25 29 33 and 37 as an interconnection between adjacent portions of the channel 10 as is shown in fig1 these portions of the channel 10 are identified by reference numerals 11 13 15 17 and 19 a next step in the manufacture of the sliding patio door according to the present invention contemplates the insertion of at least two corner locks into the mitered cuts which form the two corners along the bottom of the door after construction for purposes of this disclosure these corners are arbitrarily selected as being the corners defined by mitered sides 24 26 and 36 38 however as will be understood by those skilled in the art the bottom corners may be fabricated at other locations along the channel 10 it will also be understood that the preferred construction will include a corner lock in all four corners of the door the particular features of the corner lock in accordance with the present invention are shown in fig3 and 4 one of the corner locks referred to by the reference numeral 40 includes a first end 42 as is shown in the cross section of fig4 the corner lock 40 is formed from a length of extruded material having opposing sides 50 52 with an extension 53 extending normal from the surface 50 into the space between the two surfaces 50 52 the extremity of the extension has a bevel.