I will not cover all the indexes you can find at https://www.php.net/manual/en/reserved.variables.server.php, only those that relate to some parent folder of the current file, the current file itself, or any other path.
The test was done by having the file _SERVER.php print out the values I was interested in, and I placed this file in the folder subfolder, which was in turn located in the root of the website/localhost. I called the script itself with the query string a=b, so the full address was: localhost/subfolder/_SERVER.php?a=b
Here are the results:
PHP_SELF: /subfolder/_SERVER.phpSCRIPT_NAME: /subfolder/_SERVER.phpORIG_PATH_INFO: /subfolder/_SERVER.php
DOCUMENT_ROOT: F:\Mona\Visual Studio 2012\Projects\PhpLearn\PhpLearnHTTP_HOST: localhostSCRIPT_FILENAME: F:\Mona\Visual Studio 2012\Projects\PhpLearn\PhpLearn\subfolder\_SERVER.phpPATH_TRANSLATED: F:\Mona\Visual Studio 2012\Projects\PhpLearn\PhpLearn\subfolder\_SERVER.php
REQUEST_URI: /subfolder/_SERVER.php?a=b