diff --git a/externs/texttrack.js b/externs/texttrack.js
index eb08617ca2..d792eb4b9a 100644
--- a/externs/texttrack.js
+++ b/externs/texttrack.js
@@ -33,3 +33,15 @@ TextTrackCue.prototype.positionAlign;
 
 /** @type {string} */
 TextTrackCue.prototype.lineAlign;
+
+
+/** @type {number|null|string} */
+TextTrackCue.prototype.line;
+
+
+/** @type {string} */
+TextTrackCue.prototype.vertical;
+
+
+/** @type {boolean} */
+TextTrackCue.prototype.snapToLines;
diff --git a/lib/media/ttml_text_parser.js b/lib/media/ttml_text_parser.js
index 2f69d594e5..321ee31a39 100644
--- a/lib/media/ttml_text_parser.js
+++ b/lib/media/ttml_text_parser.js
@@ -336,6 +336,12 @@ shaka.media.TtmlTextParser.addStyle_ = function(
         cue.position = Number(results[1]);
         cue.line = Number(results[2]);
       }
+      // A boolean indicating whether the line is an integer
+      // number of lines (using the line dimensions of the first
+      // line of the cue), or whether it is a percentage of the
+      // dimension of the video. The flag is set to true when lines
+      // are counted, and false otherwise.
+      cue.snapToLines = false;
     }
   }