Description:
------------
The manual at following address doesn't explain what kind of constants you may define.
http://www.php.net/manual/en/language.oop5.constants.php
I've tried to use bits but PHP 5 generates a parse errors on those as well.
Either add in the documentation which are allowed or extend the use of const.

Reproduce code:
---------------
<?php
class bar
{
    const ASSOC = 1<<0; # CRASH
    const SQL_ASSOC = MYSQL_ASSOC; # Works
}
?>

Expected result:
----------------
A constant bit

Actual result:
--------------
Parse error: syntax error, unexpected T_SL, expecting ',' or ';'