SPField.PrimaryPIAttribute property
SharePoint 2013
Gets or sets an alternate attribute in the document processing instruction, specified by the PrimaryPITarget property, that is used as the column value in property promotion and demotion in XML documents.
Assembly: Microsoft.SharePoint (in Microsoft.SharePoint.dll)
Property value
Type: System.StringA string that contains the alternate attribute in the document processing instruction that is used as the column value.