$header_name} before any output. This means the opening "<:" have to be
the first characters in your document, without any whitespace in front
of them. If you start output and try to set headers later, an error
$header_name} before any output. This means the opening "<:" have to be
the first characters in your document, without any whitespace in front
of them. If you start output and try to set headers later, an error