+ /**
+ * Contextually filter a post revision field.
+ *
+ * The dynamic portion of the hook name, $field, corresponds to each of the post
+ * fields of the revision object being iterated over in a foreach statement.
+ *
+ * @since 3.6.0
+ *
+ * @param string $compare_from->$field The current revision field to compare to or from.
+ * @param string $field The current revision field.
+ * @param WP_Post $compare_from The revision post object to compare to or from.
+ * @param string null The context of whether the current revision is the old or the new one. Values are 'to' or 'from'.
+ */