-In this hash, you can set headers. Underscores are converted to normal minus
-signs, so you can leave out quotes. The hash is case insensitive: the case used
+This is a hash of HTTP headers to accompany the first output.
+By default it will contain C<X-PLP-Version> to identify the serving module,
+and C<Content-Type> set to C<text/html>.
+
+If STDOUT has been opened as :utf8,
+a C<charset=utf-8> attribute will automatically be added.
+This will not be possible with FastCGI
+because FCGI (as of version 0.74) does not support output layers.
+
+Headers can be added and/or changed as long as they have not yet been sent.
+Underscores in key names are converted to normal minus signs,
+so you can leave out quotes. The hash is case insensitive: the case used