[TYPO3] All environment-safe server and environment variables?

[Bing Du]

Hello,

On 
http://typo3.org/documentation/document-library/core-documentation/doc_core_api/current/view/3/2/,
It just gives five env variable examples for t3lib_div::getIndpEnv. 
Where can I find all the environment-safe server  and environment 
variables?

Thanks in advance,

Bing