Woah there! Sure WSGI specified this -- they just got it totally wrong [1] :)
[1]
http://www.wsgi.org/wsgi/WSGI_2.0#decoding-script-name-path-info -- originally added by Ian Bicking 01-24-2008
Unless someone beats me to it, I'll start compiling the comments from the few big JSGI threads into Level0/A and Level1/A proposals, with Level0/A being as close as possible to current JSGI while addressing any remaining problems, and Level1/A being the
greatest hits from the many request object suggestions while remaining compatible with Level0/A-compliant middleware.