Patent claim: A rear post 1 for inwall frames of retractable sliding doors which is substantially shaped characterized in that it has axial coupling means 4 that cooperate with means of engagement and centering 6 which protrude from a flat second base 7 of a Cshaped extension 8 said rear post 1 and extension 8 being selectively lockable in position by way of temporary locking means 12a 12b.

Related passage: Also taking the Figures as a reference it is observed that this invention see Figure 1 is made up of a counterframe for a concealed sliding door with a levelling device particularly adapted to counterframe structures for concealed sliding doors of the type to be integrated into walls such as for example partition walls in plasterboard or in stone with plaster covering wherein said counterframe structure is of the conventional type and includes a series of fixed elements intended to be integrated into the wall structure as well as a series of movable parts intended to be used during the installation stage.The fixed elements mentioned provided are associated with the wall structure and include at least one casing 100 intended to constitute the structure within which the door will be contained once it has been made to slide until reaching the opening position in addition to a door post intended to be fixed to the wall in correspondence with the vertical profile of the door frame opposite positioning profile of the casing mentioned.The base of the casing 110 coinciding with the lower side of the casing 100 provided in the example provides connecting transversal elements 70 80.Furthermore the counterframe is provided to comprise at least one first support device 1 engaged to the base of the casing 110 and in more detail in the example is engaged to the connecting transversal elements 70 80 of the counterframe and a second support device 2 engaged to the door post 90 of the counterframe wherein both the first support device 1 as well as the second support device 2 are structured in such a way as to be adjustable.In the majority of the embodiment example described both the first support device 1 as well as the second support device 2 include a bracket 10 20 that is Lshaped and provided in correspondence with the centre of the horizontalportion 101 201with a through hole 1 02 202 for the engagement of the bracket 10 20 usually by means of a nail or a fastening screw to the concrete slabs of the floor.Furthermore in correspondence with the vertical portion 103 203 the bracket 10 20 is provided with horizontal openings 104 204 that are equidistant and parallel to each other.In the first support device 1 at least one horizontal opening 104 constitutes a seat for engagement usually through the bolting of an adjustable square 30 that is superimposed and slideable in relation to the bracket 1020 said adjustable square 30 consisting of a vertical wall 301 that is orthogonal to a horizontal wall 303 wherein the adjustable square 30 in correspondence to the vertical wall 301 is provided with guide openings 302 which are arranged vertically as well as equidistant and parallel in relation to each other.The provision of the horizontal openings 104 of the bracket 10 and of guide openings 302 with which the adjustable square 30 is provided allows the execution of the adjustment of the adjustable square 30 in relation to the bracket 10 both in the vertical as well as horizontal direction thus allowing the adjustment and fixing in position judged to most convenient for levelling.The horizontal wall 303 of the square 30 is provided to be hooked to a shaped support body 4050.In more detail in the example the horizontal wall 303 of the adjustable square 30 is to be held by a holding track 401 501 that is provided on the lower part of the base wall 402 502 of the shaped support body 40 50.In the embodiment example described the holding track 401 501 is produced by means of the suitable cutting and folding of the portion cut in such a way as to produce the holding track 401 501 so that is made up of two guide elements 411 412 511 512 symmetric and specular to each other which are shaped in such a way as to form two Lshaped projecting flanges.The shaped support body 40 50 is provided with two side walls 403 404 503 504 orthogonal to the base wall 402 502.In a first variant theside walls 403 404 of the shaped support body 40 are to be flat each being symmetrical and parallel in relation to the other wherein each of the two side walls 403 404 is further to form an angle with the base wall 402 equal to 92.In the detail of the embodiment example described the internal measurement of the base wall 402 is equal to 58 mm while the measurement of each of the two side walls 403 404 is internally equal to 43 mm and externally equal to 44.16 mm.In a second variant provision is made for the side walls 503 504 of the shaped support body 50 to be shaped like a step so that in correspondence with the two opposite lateral ends of the base wall 502 for each of the two shaped walls 503 504 a first vertical portion 531 541 is produced orthogonal to the base wall 502 and orthogonally to the first vertical portion 531 541 is a horizontal portion 532 542 which continues with a second vertical portion 533 543 orthogonal in relation to the horizontal portion 532 542.In the description of the embodiment provision is made for the measurement of the base wall 502 of the second type of shaped support body 50 measured between the two shaped walls 503 504 of said body to be equal to 53 mm while each first vertical portion 531 541 of each of the two shaped walls 503 504 is to have a height equal to 16.8 mm while the measurement of the width of the horizontal portion 532 542 is 9.8 mm moreover the measurement of the height of the second vertical portion 533 543 is to be 12 mm so that that the intervening distance between the second vertical portion 533 543 of the two shaped walls 503 504 is 75 mm.The second support device 2 provides bolted to the bracket 20 an adjustable support element 60 that is superimposed and slideable in relation to the bracket 20 consisting of a metallic plate provided with guide openings 601 that are vertical parallel and reciprocally equidistant for the height adjustment of said plate.In correspondence with the end upperthe adjustable support element 60 is further equipped with a clamping fork 602 obtained by means of the external folding of a cut portion.In practice once the installation of the counterframe and its correct levelling in relation to the surface floor surface is underway with the suitable progression to the adjustment both of the first support device 1 as well as the second support device 2said devices will remain embedded in the floor.