referring to the drawings in greater detail , fig1 - 7 show a first embodiment of the invention ; fig8 - 13 show a second embodiment of the invention ; and fig1 and 15 show a third embodiment of the invention . referring first to fig1 - 3 , the invention is incorporated in a first embodiment of a mating connector assembly , generally designated 24 , which includes a backplane connector assembly , generally designated 26 , mateable with a daughterboard connector assembly , generally designated 28 . the backplane connector assembly is mounted in an aperture 30 in a substrate , panel or backplane 32 which , in the preferred embodiment , is a printed circuit board . specifically , backplane 32 can be considered the “ motherboard ” herein . the daughterboard connector assembly is mounted on a top surface of a second printed circuit board 34 which is considered the “ daughterboard ” herein . backplane connector assembly 26 includes an adapter , generally designated 36 , which is mounted in aperture 30 in motherboard 32 . four fiber optic connector modules , generally designated 38 , are inserted into adapter 36 , through aperture 30 , from the front of backplane 32 . each fiber optic connector module is terminated to a multi - fiber cable 40 . each cable is a flat or “ ribbon ” cable having a plurality of optical fibers . after daughterboard connector assembly 28 is mounted on daughterboard 34 , four fiber optic connector modules , generally designated 42 , are inserted into the back of the connector housing , as described hereinafter . each module 42 is terminated to a flat , multi - fiber cable 44 similar to fiber optic cables 40 . backplane connector assembly 26 and daughterboard connector assembly 28 are mateable in the direction of arrows “ a ” ( fig1 and 2 ) to a mated condition shown in fig3 wherein the fibers of cables 40 and 44 are functionally connected . adapter 36 of the backplane connector assembly is fixed to backplane 32 by a pair of fasteners 46 . the adapter includes a housing 48 and a pair of flexible latch arms 50 spaced outwardly from opposite sides of the housing . the housing also has a pair of outwardly projecting alignment ribs 52 on opposite sides thereof . at this point , reference is made to fig1 where three intersecting arrows “ x ”, “ y ” and “ z ” are shown . arrow “ x ” represents a direction generally parallel to daughterboard 34 . arrow “ y ” represents a direction generally perpendicular to the daughterboard . arrow “ z ” represents a direction generally parallel to the daughterboard but corresponding to the mating direction of the connector assemblies as described above by arrows “ a ”. in other words , direction “ x ” is transversely of the mating direction of the connector assemblies . [ 0036 ] fig4 shows daughterboard connector assembly 28 to include a connector housing , generally designated 54 , adapted for mounting on top of daughterboard 34 . the housing is molded of dielectric material such as plastic or the like and includes four through passages or receptacles 56 for receiving fiber optic connector modules 42 in the direction of arrow “ b ”. the housing has a pair of forwardly projecting alignment flanges 58 at opposite sides thereof and between which housing 48 ( fig1 ) of adapter 36 is inserted . alignment ribs 52 on opposite sides of the adapter housing ride into grooves 60 on the insides of alignment flanges 88 . a pair of latch ribs 62 also are provided on opposite sides of housing 54 for engagement by latch arms 50 of adapter 36 . a bottom flange 64 projects forwardly of housing 54 flush with a bottom surface 66 of the housing . the flange has a bottom hook portion 64 a and a top chamfered portion 64 b . the bottom hook portion overlaps an edge 68 of daughterboard 34 . the top chamfered portion is engageable by the front bottom edge of adapter housing 48 to prevent the bottom edge of the adapter housing from “ stubbing ” the front edge of the daughterboard during mating of the connector assemblies . the invention contemplates that connector housing 54 of daughterboard connector assembly 28 includes elongated channels , generally designated 70 , on opposite sides thereof for receiving a pair of elongated fastening posts , generally designated 72 . as will be described in greater detail hereinafter , the fastening posts are snap - fit into the channels to preload positions so that they can be transported and manipulated as a subassembly with housing 54 . a pair of fasteners in the form of externally threaded bolts 74 are inserted from the bottom of daughterboard 34 in the direction of arrows “ c ”, through holes 76 in the daughterboard , and into the bottoms of fastening posts 72 , as will be seen in greater detail hereinafter . the bolts tighten fastening posts 72 to daughterboard 34 , leaving connector housing 54 ( i . e ., daughterboard connector assembly 28 ) with floating movement relative to the daughterboard , all of which will be seen hereinafter . fig5 a - 5 c show that each fastening post 72 is elongated , generally cylindrical and includes a pair of enlarged heads 78 at opposite ends thereof . the bottom of each fastening post is internally threaded , as at 80 , for receiving a respective one of the bolts 74 to tighten the fastening post onto the top of daughterboard 34 . the top of each fastening post includes a hexagonal socket 82 for receiving a wrench to prevent rotation of the fastening post while the bolt is threaded thereinto or to disassemble the assembly from the daughterboard if necessary . generally , fig6 shows how fastening posts 72 within channels 70 provide for floating movement of connector housing 54 and , therefore , daughterboard connector assembly 28 , relative to daughterboard 34 in the “ x ” direction described above , i . e ., generally parallel to daughterboard 34 and generally perpendicular to the mating direction “ z ” of the connector assemblies . first of all , fig6 shows that each channel 70 has a restricted mouth 84 which is slightly narrower than the diameter of the respective fastening post 72 between heads 78 thereof . therefore , the fastening posts can be snap - fit into the channels , past the restricted mouths 84 of the channels , to a preload position to facilitate handling and manipulation of the connector assembly without the fastening posts falling away therefrom . [ 0040 ] fig6 shows that each fastening post 72 has a cross - dimension substantially equal to the cross - dimension of the interior of channel 70 in the “ z ” direction . this prevents any floating movement of the housing relative to the daughterboard in the “ z ” or mating direction of the connector assemblies . on the other hand , the cross - dimension of the interior of each channel 70 , i . e ., between restricted mouth 84 and a base or bottom 86 of the channel , is larger than the cross - dimension of the fastening post . this differential in the dimensions is shown by arrows “ d ”. this differential allows for floating movement of housing 54 and daughterboard connector assembly 28 relative to daughterboard 34 in the direction of arrow “ x ”, i . e ., generally parallel to the daughterboard and generally perpendicular to the mating direction of the connector assemblies . generally , fig7 shows the amount of floating action between connector housing 54 and daughterboard connector assembly 18 relative to daughterboard 34 in a direction generally perpendicular to the daughterboard . more particularly , it can be seen that each fastening post 72 is longer than its respective channel 70 . each channel has top and bottom ends 88 and 90 , respectively . each fastening post 72 has enlarged heads 78 as described above . these heads abut opposite ends of the respective channel . however , it can be seen in fig7 that bottom end 90 of the channel is recessed , as at 92 , to accommodate the bottom head 78 of the fastening post so that the connector housing can move flush downwardly onto the top of the daughterboard rather than constantly engaging the relatively small head of the fastening bolt . in any event , the length of the fastening bolt , between enlarged heads 78 , is longer than the effective length of the post - receiving channel so that floating movement of connector housing 54 and daughterboard connector assembly 28 relative to daughterboard 34 is provided as indicated by arrows “ e ”. this floating movement is in the “ y ” direction described above , i . e ., generally perpendicular to daughterboard 34 and generally perpendicular to the mating direction of the connector assemblies as indicated by both arrows “ a ” and “ z ”. fig8 - 13 show a second embodiment of the invention wherein a mating connector assembly , generally designated 24 a , includes a backplane connector assembly , generally designated 26 a , mateable with a daughterboard connector assembly , generally designated 28 a . backplane connector assembly 26 a includes a pair of adapters 36 one on top of another and mounted in a pair of apertures 30 motherboard 32 . daughterboard connector assembly 28 a includes a pair of connector housings 54 stacked one on top of the other on top of daughterboard 34 . otherwise , connector assemblies 26 a and 28 a are the same as connector assemblies 26 and 28 described above in relation to fig1 - 7 . consequently , like reference numerals have been applied in fig8 - 13 to refer to like components described above in relation to the first embodiment of fig1 - 7 . the descriptions and functions of those components will not be repeated in order to avoid unnecessarily expanding the specification . the major difference between the second embodiment of fig8 - 13 and the first embodiment of fig1 - 7 is that a single elongated fastening post , generally designated 72 a , is snap - fit in each pair of vertically aligned channels 70 of the pair of connecting housings 54 of daughterboard connector assembly 28 a . the pair of elongated fastening posts 72 a perform the dual function of mounting the connector housings on daughterboard 34 as well as stacking the housings one on top of another , and in a spaced relationship . elongated fastening posts 72 a of the second embodiment are best shown in fig1 - 13 . like fastening posts 72 of the first embodiment , each fastening post 72 a of the second embodiment is elongated , generally cylindrical and includes a pair of enlarged heads 78 at opposite ends thereof . the bottom of each fastening post is internally threaded , as at 80 , for receiving a respective one of the bolts 74 to tighten the fastening posts onto the top of daughterboard 34 . the top of each fastening post includes the hexagonal socket 82 for receiving a wrench to prevent rotation of the fastening post while the bolt is threaded thereinto or to disassemble the assembly from the daughterboard if necessary . other than the fact that fastening posts 72 a are longer than fastening posts 72 to accommodate the pair of stacked connector housings , each fastening post 72 a of the second embodiment includes a ring - like peripheral flange 96 projecting outwardly of the post generally equidistant between opposite ends of the post . as best seen in fig1 , flange 96 functions as a spacer to vertically space the pair of connector housings 54 from each other above daughterboard 34 . like the first embodiment , fastening posts 72 a of the second embodiment are dimensioned relative to channels 77 to provide for floating movement in the “ x ”, “ y ” and “ z ” directions . in addition , both connector housings 54 , with or without modules 42 , can be assembled to a pair of fastening posts 72 a to comprise a subassembly for manipulation and handling . [ 0046 ] fig1 and 15 show a third embodiment of the invention which , like the second embodiment of fig8 - 13 , a daughterboard connector assembly 28 b is structured for stacking a pair of connector housings 54 one on top of another on top of daughterboard 34 . again , like reference numerals have been applied in fig1 and 15 to refer to like components described above in relation to the first and second embodiments of fig1 . in addition , the respective descriptions of the structure and function of the components will not be repeated . in the third embodiment of fig1 and 15 , a pair of the elongated fastening posts 72 of the first embodiment are snap - fit into channels 70 of each connector housing 54 to provide a pair of subsassemblies for handling and manipulation and to provide for floating movement of the connector housings relative to daughterboard 34 in the “ x ”, “ y ” and “ z ” directions . the bottom - most connector housing is connected to the daughterboard the same as described above in relation to the first embodiment of fig1 - 7 . however , fig1 best shows the configuration of a bridging bracket , generally designated 98 , which mounts the top - most connector housing spaced above the bottom housing . the bridging bracket is configured in an inverted , generally u - shape , including a pair of depending leg portions 98 a joined by a bridge portion 98 b . a flange 98 c projects outwardly from the bottom of each leg portion and includes a pair of holes 100 for receiving a pair of bolt - like fasteners 102 projecting upwardly from daughterboard 34 . holes 100 may be internally threaded for receiving externally threaded fasteners 102 . a pair of externally threaded fasteners 74 extend upwardly through bridge portion 98 b of bracket 98 for threading into fastening posts 72 of the top - most connector housing 54 . in assembling daughterboard connector assembly 28 b , the bottom - most connector housing 54 is assembled to daughterboard 34 as shown in fig1 the same as with the first embodiment of fig1 - 7 . bridging bracket 98 then is assembled to the daughterboard by using fasteners 102 . the top connector housing 54 then is mounted on top of the bridging bracket . in an alternative assembly procedure , bridging bracket 98 could be assembled to the top connector housing by using fasteners 74 through bridge portion 98 b of the bracket before mounting to daughterboard 34 . the bracket and the top connector housing , thereby , can comprise an additional subassembly to facilitate handling and manipulation and to more easily thread fasteners 74 from within the bridging bracket . in either the second embodiment of fig8 - 13 or the third embodiment of fig1 and 15 , it can be seen that high density interconnections can be made on daughterboard 34 without using up additional space or “ real estate ” on the daughterboard or substrate . with the second embodiment of fig8 - 13 , two or more connector housings can be stacked on top of each other , using the same amount of space on daughterboard 34 as a single connector housing . the connectors are spaced from each other and can work independently to increase the connection density without increasing the space on the subjacent substrate or daughterboard . it will be understood that the invention may be embodied in other specific forms without departing from the spirit or central characteristics thereof . the present examples and embodiments , therefore , are to be considered in all respects as illustrative and not restrictive , and the invention is not to be limited to the details given herein .