Some of the uploaded files will have been created for specific applications and interactive whiteboards. There are some viewers available, or alternatively there are limited trial versions that you can install. AU - AUs are audio files that can be opened in most Windows and Mac audio software including Apple QuickTime and Windows Media Player. DOCX, XLSX and PPTX - Microsoft has some online file converters and viewers that allow you to open files created by different versions of Office. These files can also be opened in iWork, OpenOffice and Google Docs. FLP - Promethean. Flipchart viewers are available for Windows and Mac. NOTEBOOK, XBK - These files are created using SMART Notebook software. The SMART Notebook Interactive viewer is available for download on an open license, allowing you to exchange Notebook files with any of your colleagues. PUB - These files can be opened only in Microsoft Publisher for Windows. No viewers are available but a 60-day free trial version of the software will enable you to open these files. RA - These are Real Audio files. A free download of RealPlayer is available. YAR - These files are unique to Hitachi's Starboard Interactive whiteboard. There is a free viewer for Windows available.