Note: When this phase of the request is processed, the URI has not yet been translated into a path name, therefore this directive could never be executed by Apache if it could specified within <Directory>, <Location>, <File> directives or in an .htaccess file. The only place this directive is allowed is the main configuration file, and the code for it will execute in the main interpreter. And because this phase happens before any identification of the type of content being requested is done (i.e. is this a python program or a gif?), the python routine specified with this handler will be called for ALL requests on this server (not just python programs), which is an important consideration if performance is a priority.