Index: src/src/Typeset/Boxes/Basic/stretch_boxes.cpp
===================================================================
--- src/src/Typeset/Boxes/Basic/stretch_boxes.cpp	(revision 6100)
+++ src/src/Typeset/Boxes/Basic/stretch_boxes.cpp	(working copy)
@@ -102,6 +102,13 @@
 }
 
 box
+wide_invbreve_box (path ip, SI x1, SI x2, SI penw, color col) {
+  SI width, height;
+  get_wide_parameters (x1, x2, penw, width, height);
+  return arc_box (ip, 0, -height, width, 1.1*height, 370<<6, 530<<6, penw, col);
+}
+
+box
 wide_squbr_box (path ip, SI x1, SI x2, SI penw, color col) {
   path dip= decorate_middle (ip);
   SI width= max (x2-x1, 6*penw), height= 6*penw;
Index: src/src/Typeset/Boxes/construct.hpp
===================================================================
--- src/src/Typeset/Boxes/construct.hpp	(revision 6100)
+++ src/src/Typeset/Boxes/construct.hpp	(working copy)
@@ -41,6 +41,7 @@
 box wide_vect_box (path ip, SI x1, SI x2, SI penw, color col);
 box wide_check_box (path ip, SI x1, SI x2, SI penw, color col);
 box wide_breve_box (path ip, SI x1, SI x2, SI penw, color col);
+box wide_invbreve_box (path ip, SI x1, SI x2, SI penw, color col);
 box wide_squbr_box (path ip, SI x1, SI x2, SI penw, color col);
 box wide_sqobr_box (path ip, SI x1, SI x2, SI penw, color col);
 box control_box (path ip, tree t, font fn);
Index: src/src/Typeset/Concat/concat_math.cpp
===================================================================
--- src/src/Typeset/Concat/concat_math.cpp	(revision 6100)
+++ src/src/Typeset/Concat/concat_math.cpp	(working copy)
@@ -292,6 +292,8 @@
       wideb= wide_check_box (decorate_middle (ip), b->x1, b->x2, w, env->col);
     else if (s == "<breve>")
       wideb= wide_breve_box (decorate_middle (ip), b->x1, b->x2, w, env->col);
+    else if (s == "<invbreve>")
+      wideb= wide_invbreve_box (decorate_middle (ip), b->x1, b->x2, w, env->col);
     else if (s == "<squnderbrace>" || s == "<squnderbrace*>")
       wideb= wide_squbr_box (decorate_middle (ip), b->x1, b->x2, w, env->col);
     else if (s == "<sqoverbrace>" || s == "<sqoverbrace*>")