diff --git a/reference/mysqli/mysqli/debug.xml b/reference/mysqli/mysqli/debug.xml
index f3f0e4cd01..33e1bd9a06 100644
--- a/reference/mysqli/mysqli/debug.xml
+++ b/reference/mysqli/mysqli/debug.xml
@@ -34,6 +34,71 @@
A string representing the debugging operation to perform
+
+ The debug control string is a sequence of colon separated fields as follows:
+ ::]]>
+ Each field consists of a mandatory flag character followed by an optional , and comma separated list of modifiers:
+ flag[,modifier,modifier,...,modifier]
+
+
+
+ Recognized Flag Characters
+
+
+
+ option character
+ Description
+
+
+
+
+ O
+ MYSQLND_DEBUG_FLUSH
+
+
+ A/a
+ MYSQLND_DEBUG_APPEND
+
+
+ F
+ MYSQLND_DEBUG_DUMP_FILE
+
+
+ i
+ MYSQLND_DEBUG_DUMP_PID
+
+
+ L
+ MYSQLND_DEBUG_DUMP_LINE
+
+
+ m
+ MYSQLND_DEBUG_TRACE_MEMORY_CALLS
+
+
+ n
+ MYSQLND_DEBUG_DUMP_LEVEL
+
+
+ o
+ output to file
+
+
+ T
+ MYSQLND_DEBUG_DUMP_TIME
+
+
+ t
+ MYSQLND_DEBUG_DUMP_TRACE
+
+
+ x
+ MYSQLND_DEBUG_PROFILE_CALLS
+
+
+
+
+