or square opening of a size suitable to accept the three sides of the u shaped rail 104 specifically the web 112 and two legs or sides 114 of the u shaped cross section therefore this type of fence system 102 inherently has a problem in that it provides a gap or opening that allows access to the interior of the fence post 110 in an attempt to solve this problem plugs 116 sized to fit between the leg or sides 114 of the u shaped rail 104 are inserted adjacent the fence post 110 use of the plug 116 while closing the gap or opening creates additional costs associated with both manufacturing the plugs 116 and the labor to insert the plugs 116 at each and every joint between the fence post 110 and rail 104 since this plug is inserted using only an interference fit it is unknown at this time whether exposure to the elements over time will work its way loose and expose the gap or opening in the rail referring now to fig1 there is shown a perspective view of a modular fence system 10 according to an embodiment of the present invention the modular fence system 10 in includes a fence post 12 the fence post 12 includes an upper end 14 and a lower end 16 that is embedded in the ground 18 using well known prior art teachings for anchoring the post the.