I am using Spreadsheet_Excel_Writer, which is a component of PEAR, to generate Excel files in a web application.
By default it saves in BIFF5, and I have use setVersion to change the BIFF5 version to BIFF8.
The manual says use of this function will be deprecated. Does anyone know the reason?
It was deprecated because the developers of PEAR Spreadsheet_Excel_Writer always intended to make BIFF8 the default format, and eventually to drop BIFF5 completely as Excel users migrated from Excel95 to Excel98 and later 2003, and the need for backward compatibility with the earlier version was reduced.
However, ongoing development of PEAR Spreadsheet_Excel_Writer atrophied and died before that point was reached; so the interim state remains.
In terms of risk: minimal. Most of the features of BIFF8 files can still be read by anbody still using Excel95 (the newer features of BIFF8 were never added to Spreadsheet_Excel_Writer); but most Excel users these days have moved on with Excel98 as a minimum version. The newer versions (Excel2007 and Excel2010) can still read BIFF8 files without any problem.