constants

ENTITY ENTITY
SID (
string)
Constant containing either the session name and session ID in the form of 
"name=ID" or empty string if session ID was set in an appropriate session cookie. This is the same id as the one returned by 
session_id.
This constant has been deprecated as of PHP 8.4.0.
PHP_SESSION_DISABLED (
int)
Return value of 
session_status if sessions are disabled.
PHP_SESSION_NONE (
int)
Return value of 
session_status if sessions are enabled, but no session exists.
PHP_SESSION_ACTIVE (
int)
Return value of 
session_status if sessions are enabled, and a session exists.