DOC: config: Specify %Ta is only available in HTTP mode
%Ta format can only be used in HTTP mode but it was not specify in the
configuration manual.
This patch should fix the issue #1317.
diff --git a/doc/configuration.txt b/doc/configuration.txt
index b78eaf8..6a05110 100644
--- a/doc/configuration.txt
+++ b/doc/configuration.txt
@@ -21470,7 +21470,7 @@
| | %ID | unique-id | string |
| | %ST | status_code | numeric |
| | %T | gmt_date_time | date |
- | | %Ta | Active time of the request (from TR to end) | numeric |
+ | H | %Ta | Active time of the request (from TR to end) | numeric |
| | %Tc | Tc | numeric |
| | %Td | Td = Tt - (Tq + Tw + Tc + Tr) | numeric |
| | %Tl | local_date_time | date |