-@param[in] event_class Event class of which to set the context
- field type.
-@param[in] context_type Context field type.
-@returns 0 on success, or a negative value on error.
+As of Babeltrace \btversion, if \p context_type is not \c NULL,
+\p context_type \em must be a CTF IR structure field type object.
+
+@param[in] event_class Event class of which to set the context field
+ type.
+@param[in] context_type Context field type, or \c NULL to unset the
+ current context field type.
+@returns 0 on success, or a negative value on error.