diff --git a/src/libcamera/pipeline_handler.cpp b/src/libcamera/pipeline_handler.cpp
index 433c05f6..43395b57 100644
--- a/src/libcamera/pipeline_handler.cpp
+++ b/src/libcamera/pipeline_handler.cpp
@@ -97,6 +97,17 @@ LOG_DEFINE_CATEGORY(Pipeline)
  * when creating the camera, and shall not be modified afterwards.
  */
 
+/**
+ * \var CameraData::requestSequence_
+ * \brief The queuing sequence of the request
+ *
+ * When requests are queued, they are given a per-camera sequence number to
+ * facilitate debugging of internal request usage.
+ *
+ * The requestSequence_ tracks the number of requests queued to a camera
+ * over its lifetime.
+ */
+
 /**
  * \class PipelineHandler
  * \brief Create and manage cameras based on a set of media devices