<directivesynopsis>
<name>RequestHeader</name>
<description>Configure HTTP request headers</description>
-<syntax>RequestHeader add|append|edit|edit*|merge|set|unset
+<syntax>RequestHeader add|append|edit|edit*|merge|set|setifempty|unset
<var>header</var> [<var>value</var>] [<var>replacement</var>]
[early|env=[!]<var>variable</var>]|expr=<var>expression</var>]
</syntax>
<contextlist><context>server config</context><context>virtual host</context>
<context>directory</context><context>.htaccess</context></contextlist>
<override>FileInfo</override>
+<compatibility>SetIfEmpty available in 2.4.7 and later</compatibility>
<usage>
<p>This directive can replace, merge, change or remove HTTP request
<dt><code>setifempty</code></dt>
<dd>The request header is set, but only if there is no previous header
- with this name</dd>
+ with this name. Available in 2.4.7 and later.</dd>
<dt><code>unset</code></dt>
<dd>The request header of this name is removed, if it exists. If
<directivesynopsis>
<name>Header</name>
<description>Configure HTTP response headers</description>
-<syntax>Header [<var>condition</var>] add|append|echo|edit|edit*|merge|set|unset|note
+<syntax>Header [<var>condition</var>] add|append|echo|edit|edit*|merge|set|setifempty|unset|note
<var>header</var> [<var>value</var>] [<var>replacement</var>]
[early|env=[!]<var>variable</var>]|expr=<var>expression</var>]
</syntax>
<contextlist><context>server config</context><context>virtual host</context>
<context>directory</context><context>.htaccess</context></contextlist>
<override>FileInfo</override>
-<compatibility>Default condition was temporarily changed to "always" in 2.3.9 and 2.3.10</compatibility>
+<compatibility>Default condition was temporarily changed to "always" in 2.3.9 and 2.3.10. SetIfEmpty available since 2.4.7.</compatibility>
<usage>
<p>This directive can replace, merge or remove HTTP response
<dt><code>setifempty</code></dt>
<dd>The request header is set, but only if there is no previous header
- with this name</dd>
+ with this name. Available in 2.4.7 and later.</dd>
<dt><code>unset</code></dt>
<dd>The response header of this name is removed, if it exists.