HTTP -- get HTTP headers

Called with the name of an HTTP request header field, returns its value. Capitalization and the use of hyphens versus underscores are not significant.
Request headers are sent by the browser to the server. It is not possible to access the Response headers returned to the browser.
Only returns headers permitted by site configuration. Returns '' if the header is not allowed.
When called without a parameter, nothing is returned. See VarHTTPS for other options.

The HTTP and HTTPS macros are deprecated as of Foswiki release 2.1. and will be removed in a future release.

Parameters

Name	Description
`"name"`	Name of the header to get

Write	Returns	Notes
`%HTTP%`		Always returns ''
`%HTTP{"Accept-language"}%`	en-US,en;q=0.9
`%HTTP{"User-Agent"}%`	Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/110.0.0.0 Safari/537.36
`%HTTP{"Cookie"}%`		Not allowed by default.

You can see the HTTP headers your browser sends to the server on a number of sites e.g. http://www.ericgiguere.com/tools/http-header-viewer.html