dialog Document shortest ka_interval

modules/dialog/README

@@ -12,8 +12,12 @@ Edited by
 
 Bogdan-Andrei Iancu
 
+Edited by
+
 Carsten Bock
 
+Edited by
+
 Alex Balashov
 
    <[email protected]>
@@ -1145,7 +1149,8 @@ modparam("dialog", "ka_timer", 10)
    dialog setup or previous keep-alive. The value represents the number of
    seconds.
 
-   Default value is "0" (no keep alive).
+   Default value is "0" (no keep alive). The lowest settable interval is
+   30 seconds.
 
    Example 1.49. Set ka_interval parameter
 ...

modules/dialog/doc/dialog_admin.xml

@@ -1249,7 +1249,8 @@ modparam("dialog", "ka_timer", 10)
 		</para>
 		<para>
 		<emphasis>
-			Default value is <quote>0</quote> (no keep alive).
+			Default value is <quote>0</quote> (no keep alive). The lowest
+			settable interval is 30 seconds.
 		</emphasis>
 		</para>
 		<example>