( [string name] )
session_name() returns the name of the current
session. If name is specified, the name of
the current session is changed to its value.
The session name references the session id in cookies and
URLs. It should contain only alphanumeric characters; it should
be short and descriptive (i.e. for users with enabled cookie
warnings). The session name is reset to the default value
stored in session.name at request startup
time. Thus, you need to call session_name()
for every request (and before session_start()
or session_register() are called).
The session name can't consist of digits only, at least one letter must
be present. Otherwise a new session id is generated every time.
Example 1. session_name() examples
/* set the session name to WebsiteID */
$previous_name = session_name("WebsiteID");
echo "The previous session name was $previous_name<br />";
See also the session.name