Well First Let me explain what does it mean by Promotion and Demotion
- Promotion – It means that you capture the value present in the document (*.xml or wordML or you can write your own document parser) and expose it to the SharePoint document library as a Column. What you get out of it is that you have a synchronization of the Data between the document and Column of the doc library. (When you update the document it gets automatically reflected in the document library and vise versa.)
- Demotion – It means the opposite. You capture the column of the Document Library and display it in the Document.
Well whenever you publish a InfoPath form to the SharePoint server using File->Publish, at the end of the Wizard you will be provided
with a Option that will allow you to the add the field of the InfoPath to the document. How can do that when I automation the publishing of the InfoPath using features or When I publish the form using Central Administration Website?. There is an option in InfoPath, where you can specify the fields to be promoted to the Document Library at the design time. Use Tools->Form Option -> Property Promotion