diff --git a/docs/manual/env.xml b/docs/manual/env.xml
index 72f042144a..26d2dfe99f 100644
--- a/docs/manual/env.xml
+++ b/docs/manual/env.xml
@@ -303,9 +303,11 @@
   <section id="cgi">
     <title>CGI environment variables</title>
 
-    <p>The CGI specification (<rfc section="4.1">3875</rfc>) defines a number of environment
-    variables that expand on those defined by the HTTP spec.
-    These have been adopted more broadly, and are a standard
+    <p>The CGI specification (<rfc section="4.1">3875</rfc>) defines a
+    number of meta-variables, many of which derive their values from
+    HTTP request headers. Apache httpd makes these available as
+    environment variables to CGI scripts and other request-processing
+    mechanisms. These have been adopted more broadly, and are a standard
     part of passing information between the browser and the
     server, and between processes on the server side. Here we
     discuss a few of these. For the complete list of request