title: OpenXml SimpleField vs FieldCode
body: <p>I have created a document template (Test1.docx file) which has several MERGEFields in it. When I open the template in xml, I see some of the fields as SimpleFields and some as FieldCodes. Now, if I make some changes to the template (like adding some new template fields) and save it as Test2.docx and now when I open Test2.docx as an xml file, the field which came as SimpleField in the Test1.docx file's xml comes as FieldCode in the Test2.docx file's xml, even though I have not made any changes to that specific field.
  When is a mergefield be recognized by openxml as simple field and fieldcode?</p>