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Why do I see item listed through the web flow having the <ApplicationData> values ?
There can be different reasons for items listed through the web flow having the ApplicationData values.
One of the reason could be that item was listed using the web flow but revised using api.
For Example: Lets say you listed an item-110102451752 through the web flow. At this point, there will be no ApplicationData value for this item.
Now while revising the item, the ReviseItem api was used with <ApplicationData>App-12</ApplicationData> .
If you make a GetItem call, you will now see the ApplicationData value being set for the item that was orginally listed through the web flow.
Another reason could be Item was listed through api but Relisted using web flow.
For Example: Lets say you listed an item-110102451475 using AddItem api with <ApplicationData>App-11</ApplicationData> . The item got Ended.
Now you 'Relisted' the same item via the web flow-110102451486.
Although item-110102451486 was not listed or re-listed using api, it will still have the same value in the <ApplicationData> field as the item-110102451475 that was originally listed using api.
Now if you make a GetItem call for both the items -110102451475 (listed through api) and 110102451486(re-listed through web flow), both will have the same ApplicationData value i.e. <ApplicationData>App-11</ApplicationData>