1 files changed, 4 insertions, 0 deletions
diff --git a/expr.h b/expr.h
index b7c5c15..0251d6b 100644
--- a/expr.h
+++ b/expr.h
@@ -14,6 +14,10 @@
  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.           *
  ****************************************************************************/
 
+/**
+ * The expression tree representation.
+ */
+
 #ifndef BFS_EXPR_H
 #define BFS_EXPR_H