Explain limitation of UnDefine syntax as already noted in Define.

Increase visibility of a warning, to be consistent with Define

PR 64909

(r1883417 in trunk) [skip ci]

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1883418 13f79535-47bb-0310-9956-ffa450edef68

diff --git a/docs/manual/mod/core.xml b/docs/manual/mod/core.xml
index c9b6b46e846366741efe2ec09afcc9242dba59fa..5bece88aea2f31eded0057aaac44c8918d64998b 100644 (file)
--- a/docs/manual/mod/core.xml
+++ b/docs/manual/mod/core.xml
@@ -4841,9 +4841,15 @@ certain events before failing a request</description>
     <p>This directive can be used to toggle the use of <directive module="core"
     type="section">IfDefine</directive> sections without needing to alter
     <code>-D</code> arguments in any startup scripts.</p>
-    <p>While this directive is supported in virtual host context,
-       the changes it makes are visible to any later configuration
-       directives, beyond any enclosing virtual host.</p>
+
+    <p>Variable names may not contain colon ":" characters, to avoid clashes
+    with <directive module="mod_rewrite">RewriteMap</directive>'s syntax.</p>
+
+    <note><title>Virtual Host scope and pitfalls</title>
+      <p>While this directive is supported in virtual host context,
+         the changes it makes are visible to any later configuration
+         directives, beyond any enclosing virtual host.</p>
+    </note>
 </usage>
 <seealso><directive module="core">Define</directive></seealso>
 <seealso><directive module="core">IfDefine</directive></seealso>