sealing-box: document origin

diff --git a/sealing-box.scad.m4 b/sealing-box.scad.m4
index d8ff08c968541bd35bc46b70c0f69df4a0a84cb2..2c06917da9d21e1cc29c9b28d547ae2725e6bfa6 100644 (file)
--- a/sealing-box.scad.m4
+++ b/sealing-box.scad.m4
@@ -15,6 +15,8 @@
 //      3. use the modules
 //           SealingBox_RectBox
 //           SealingBox_RectLid
+//           (origin is notional outside corner, but at level of
+//            inside of base; box extends to positive x,y,z)
 //
 // B. Complicated shapes, but harder work
 //      1. Be a .m4 file and m4_include sealing-box.scad.m4