Usage:   request_header_add field-name field-value [ acl ... ]
	Example: request_header_add X-Client-CA "CA=%ssl::>cert_issuer" all

	This option adds header fields to outgoing HTTP requests (i.e.,
	request headers sent by Squid to the next HTTP hop such as a
	cache peer or an origin server). The option has no effect during
	cache hit detection. The equivalent adaptation vectoring point
	in ICAP terminology is post-cache REQMOD.

	Field-name is a token specifying an HTTP header name. If a
	standard HTTP header name is used, Squid does not check whether
	the new header conflicts with any existing headers or violates
	HTTP rules. If the request to be modified already contains a
	field with the same name, the old field is preserved but the
	header field values are not merged.

	Field-value is either a token or a quoted string. If quoted
	string format is used, then the surrounding quotes are removed
	while escape sequences and %macros are processed.

	One or more Squid ACLs may be specified to restrict header
	injection to matching requests. As always in squid.conf, all
	ACLs in the ACL list must be satisfied for the insertion to
	happen. The request_header_add supports fast ACLs only.

	See also: reply_header_add.