diff --git a/doc/reference.xml b/doc/reference.xml
index 82acec3..b569d40 100644
--- a/doc/reference.xml
+++ b/doc/reference.xml
@@ -108,6 +108,80 @@ not supported, they are silently ignored.
+
+
+CR_PACK_FLAGS
+
+
+
+CR_PACK_FLAGSchanrange
+ arefflags
+is similar to
+CR_PACK
+but can be used to combine one or more flag bits (bitwise-ORed together in
+the flags parameter) with the other
+parameters.
+
+
+
+Depending on context, the
+chan parameter might not be a channel;
+it could be a trigger source, clock source, gate source etc. (in which case,
+the range and
+aref parameters would probably be set
+to 0), and the flags would modify the source in some
+device-dependant way.
+
+
+
+The following flag values are defined:
+
+
+ CR_ALT_FILTER
+ CR_DITHER
+ CR_DEGLITCH
+
+
+ (all the same) specify that some sort of filtering is to be done
+ on the channel, trigger source, etc.
+
+
+
+
+ CR_ALT_SOURCE
+
+
+ specifies that some alternate source is to be used for the channel
+ (usually a calibration source).
+
+
+
+
+ CR_EDGE
+
+
+ is usually combined with a trigger source number to specify that the
+ trigger source is edge-triggered if the hardware and driver supports
+ both edge-triggering and level-triggering. If both are supported,
+ not asserting this flag specifies level-triggering.
+
+
+
+
+ CR_INVERT
+
+
+ specifies that the trigger source, gate source, etc. is to be inverted.
+
+
+
+
+
+
+
RANGE_LENGTH (deprecated)