Two-way connections between classes

Often it is useful to establish a two-way link that users can traverse in either direction. In an earlier example we established a one way link between the ?TShirt "sam55" and the ?Store "Tom's DryGoods". A user who happened upon "sam55" could exploit the link and move to "Tom's DryGoods". However, a user starting at "Tom's DryGoods" would not be able to move directly to sam55.

Here is what is required inside ?TShirt and ?Store to provide links in both directions. Inside ?TShirt is the structure

          Store UNIQUE ?Store //one store per t-shirt

just like before. Store looks this way:

?Store Address Street Text
               City Text
               State Text
               Zip Text
       Phone Text
       TShirt ?TShirt //many t-shirts can come from
                      //the same store

Enter the following data:

TShirt : sam38
Store : Woolworth's
 
Store : Woolworth's
TShirt : sam38

Now users will be able to traverse from sam38 to Woolworth's and back again:

Note the curator must provide the data for both links. Leaving out data for either one results in a one-way link, even though the model can support links in both directions. This is a drawback that can be overcome by XREF.

Show me the whole t-shirt model again.

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