-  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 
  Examples 
          
   
 HTTPS, 
REMOTE_ADDR, 
REMOTE_PORT, 
REMOTE_USER