QUERY_STRING REQUEST_URI SCRIPT_NAME PATH_INFO PATH_TRANSLATED 都是干啥的

http://testtest.com/test/info.php/virtualdir/?a=1&b=1

QUERY_STRING a=1&b=1
REQUEST_URI /test/info.php/virtualdir/?a=1&b=1
SCRIPT_NAME /test/info.php
PATH_INFO /virtualdir/
PATH_TRANSLATED D:\wwwroot\virtualdir\
DOCUMENT_ROOT D:/wwwroot
SCRIPT_FILENAME D:/wwwroot/test/info.php