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/structures.rst b/Doc/c-api/structures.rst
index 8833a36..fdee5f9 100644
--- a/Doc/c-api/structures.rst
+++ b/Doc/c-api/structures.rst
@@ -314,7 +314,7 @@
    handles use of the :keyword:`del` statement on that attribute more correctly
    than :c:macro:`T_OBJECT`.
 
-   :attr:`flags` can be 0 for write and read access or :c:macro:`READONLY` for
+   :attr:`flags` can be ``0`` for write and read access or :c:macro:`READONLY` for
    read-only access.  Using :c:macro:`T_STRING` for :attr:`type` implies
    :c:macro:`READONLY`.  Only :c:macro:`T_OBJECT` and :c:macro:`T_OBJECT_EX`
    members can be deleted.  (They are set to *NULL*).