Data liberation

The idea is that it should be easy to get data in and out of OpenPetra.org

XML/YML/CSV support

XML: advantages: easier to handle from external programs, they can transform the data
YML: advantages: easy to read and write for manual adjustments
CSV: advantages: edit long lists; problems: Excel reformats and may cut off account codes etc

http://www.codeguru.com/csharp/csharp/cs_data/xml/article.php/c16311 How to Read and Write ODF/ODS Files (OpenDocument Spreadsheets)
http://opendocument4all.com/content/view/13/29/ "AODL has been started by Lars Behrmann as a independent C# library for all kinds of ODF processing and in February 2007 it has become the .net module of the OpenOffice.org ODF Toolkit project. The library is completly written in pure C# and can be used to extend your .net based software to support the OpenDocument Format."

see http://stackoverflow.com/questions/151005/create-excel-xls-and-xlsx-file-from-c
see http://www.leniel.net/2009/07/creating-excel-spreadsheets-xls-xlsx-c.html
see http://npoi.codeplex.com/ "This project is the .NET version of POI Java project at http://poi.apache.org/. POI is an open source project which can help you read/write xls, doc, ppt files. It has a wide application."
see http://excelpackage.codeplex.com/ "ExcelPackage provides server-side generation of Excel 2007 spreadsheets. It is a set of classes and wrappers around the .NET 3.0 System.IO.Packaging API and the new Office Open XML file format."
http://www.carlosag.net/Tools/ExcelXmlWriter/