(no version information, might be only in CVS)
Get header(s) about to be sent.
In Apache2 this only works for PHP-5.1.3 and greater.
specifies the name of the header to read;
if empty or omitted, an associative array with all headers will be returned
Returns either a string containing the value of the header matching name,
FALSE on failure, or an associative array with all headers.