Issue #28496: Mark up constants 0, 1 and -1 that denote return values or
special input values as literal text.
diff --git a/Doc/c-api/marshal.rst b/Doc/c-api/marshal.rst
index b82cc96..76120ae 100644
--- a/Doc/c-api/marshal.rst
+++ b/Doc/c-api/marshal.rst
@@ -13,8 +13,8 @@
 
 Numeric values are stored with the least significant byte first.
 
-The module supports two versions of the data format: version 0 is the
-historical version, version 1 (new in Python 2.4) shares interned strings in
+The module supports two versions of the data format: version ``0`` is the
+historical version, version ``1`` (new in Python 2.4) shares interned strings in
 the file, and upon unmarshalling.  Version 2 (new in Python 2.5) uses a binary
 format for floating point numbers.  *Py_MARSHAL_VERSION* indicates the current
 file format (currently 2).