diff --git a/CMakeLists.txt b/CMakeLists.txt
index b570c27..b6363ee 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -93,3 +93,8 @@ include(CPack)
 if (NOT CMAKE_BUILD_TYPE)
   set(CMAKE_BUILD_TYPE MinSizeRel CACHE STRING "Choose the type of build, options are: None Debug Release RelWithDebInfo MinSizeRel." FORCE)
 endif ()
+
+add_custom_target(
+    print_build_type 
+    COMMAND ${CMAKE_COMMAND} -E echo $<$<CONFIG:>:Undefined>$<$<NOT:$<CONFIG:>>:$<CONFIG>>
+)
diff --git a/doc/teapot.lyx b/doc/teapot.lyx
index cd3ebc0..6ab5ff7 100644
--- a/doc/teapot.lyx
+++ b/doc/teapot.lyx
@@ -8463,7 +8463,14 @@ l1
 l1
 \emph default
  defaults to the current location.
- The second form simply returns the number of its arguments which are nonempty.
+ If any dimension of either location is negative, that component is simply
+ taken as 0.
+ In other words, locations off the sheet are considered empty, but it is
+ not an error to access them.
+\begin_inset Newline newline
+\end_inset
+
+The second form simply returns the number of its arguments which are nonempty.
 \end_layout
 
 \begin_layout Description
diff --git a/src/common/misc.c b/src/common/misc.c
index c3fa89f..a2dbfeb 100644
--- a/src/common/misc.c
+++ b/src/common/misc.c
@@ -30,16 +30,15 @@
 #include "utf8.h"
 /*}}}*/
 
-/* posorder    -- sort two integers */ /*{{{*/
+/* posorder    -- sort two integers, clamping each to be nonnegative. */ /*{{{*/
 void posorder(int *x, int *y)
 {
   assert(x != (int*)0);
-  assert(*x >= 0);
   assert(y != (int*)0);
-  assert(*y >= 0);
+  if (*x < 0) *x = 0;
+  if (*y < 0) *y = 0;
 
-  if (*x > *y)
-  {
+  if (*x > *y) {
     int t = *x;
     *x = *y;
     *y = t;