diff --git a/doc/file_hob_spec.txt b/doc/file_hob_spec.txt
new file mode 100644
index 0000000..635d23d
--- /dev/null
+++ b/doc/file_hob_spec.txt
@@ -0,0 +1,8 @@
+xB other
+Vertices
+{
+  2B int X
+  2B int Y
+  2B int Z
+  2B int ?
+}