On 2013.05.07 20:28, Neil Hodgson wrote: > http://support.microsoft.com/kb/74496 > http://en.wikipedia.org/wiki/Nul_%28band%29 I can indeed confirm that at least 'nul' cannot be used as a filename. However, I add an extension to the file names to identify them as caches. -- CPython 3.3.1 | Windows NT 6.2.9200 / FreeBSD 9.1