i have search for long time, but there are no any further documents or details of how to use this field
other than this:
https://wordmvp.com/FAQs/TblsFldsFms/AddInFields.htm
we can see EndNote software can make this
{ADDIN EN.CITE <EndNote><Cite><RecNum>0</RecNum><Note>MyAddInField</Note><DisplayText>MyAddInField</DisplayText></Cite></EndNote>}
and the field result is: MyAddInField
my question is: how can we make that done? to add our own filed or use addin field like EndNote done.