Clarifies advice around quoting regular expressions.

Submitted by: nisbet-hubbard <87453615+nisbet-hubbard@users.noreply.github.com>

Github: closes #379


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1915443 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/docs/manual/mod/mod_rewrite.html.en.utf8 b/docs/manual/mod/mod_rewrite.html.en.utf8
index 44e73c8..a8cac2d 100644
--- a/docs/manual/mod/mod_rewrite.html.en.utf8
+++ b/docs/manual/mod/mod_rewrite.html.en.utf8
@@ -1628,4 +1628,4 @@
     prettyPrint();
 }
 //--><!]]></script>
-</body></html>
\ No newline at end of file
+</body></html>
diff --git a/docs/manual/mod/mod_rewrite.xml b/docs/manual/mod/mod_rewrite.xml
index 9f4200e..160f3a8d 100644
--- a/docs/manual/mod/mod_rewrite.xml
+++ b/docs/manual/mod/mod_rewrite.xml
@@ -49,6 +49,9 @@
       sub-processing, external request redirection, or internal proxy
       throughput.</p>
 
+      <p>A regular expression only needs quoting if it contains unescaped space, 
+      in which case single and double quotes are equivalent.</p>
+
       <p>Further details, discussion, and examples, are provided in the
       <a href="../rewrite/">detailed mod_rewrite documentation</a>.</p>
 </summary>
diff --git a/docs/manual/mod/mod_setenvif.html.en.utf8 b/docs/manual/mod/mod_setenvif.html.en.utf8
index 943dc78..ed4ad51 100644
--- a/docs/manual/mod/mod_setenvif.html.en.utf8
+++ b/docs/manual/mod/mod_setenvif.html.en.utf8
@@ -365,4 +365,4 @@
     prettyPrint();
 }
 //--><!]]></script>
-</body></html>
\ No newline at end of file
+</body></html>
diff --git a/docs/manual/mod/mod_setenvif.xml b/docs/manual/mod/mod_setenvif.xml
index 99c302f..71eebf6 100644
--- a/docs/manual/mod/mod_setenvif.xml
+++ b/docs/manual/mod/mod_setenvif.xml
@@ -59,6 +59,13 @@
    are not separately evaluated in the subrequest due to the API phases
    <module>mod_setenvif</module> takes action in.</p>
 
+   <p>A regular expression only needs quoting when it contains space, 
+   in which case single and double quotes are equivalent. Unlike 
+   <module>mod_rewrite</module>, <module>mod_setenvif</module> strips every 
+   other backslash when parsing the expression; thus <code>\\</code> 
+   requires <code>\\\</code>, and <code>\\\</code> requires 
+   <code>\\\\\</code>.</p>
+
 </summary>
 
 <seealso><a href="../env.html">Environment Variables in Apache HTTP Server</a></seealso>