+ /** There are two SMPTE standards describing subtitles, 428-7:2010 and 428-7:2014, and they
+ * have different interpretations of what Vposition means. Though libdcp does not need to
+ * know the difference, this variable stores the standard from the namespace that this asset was
+ * written with (or will be written with).
+ */
+ SubtitleStandard _subtitle_standard;
+
+ std::vector<std::shared_ptr<SMPTELoadFontNode>> _load_font_nodes;
+ /** UUID for the XML inside the MXF, which should be the same as the ResourceID in the MXF (our _resource_id)
+ * but different to the AssetUUID in the MXF (our _id) according to SMPTE Bv2.1 and Doremi's 2.8.18 release notes.
+ * May be boost::none if this object has been made from an encrypted object without a key.
+ */
+ boost::optional<std::string> _xml_id;