Gets or sets default header.
This property is simply written to Excel file and has no effect on the behavior of this library.
The header string may contain special commands, for example placeholders for the page number, current date, or text formatting attributes. These fields are represented by single letters (exception: font name and size) with a leading ampersand. If the ampersand is part of the regular header text, it will be duplicated.
For more information consult Microsoft Excel documentation.
SheetHeaderFooter Class | GemBox.Spreadsheet Namespace