diff --git a/devine/core/manifests/dash.py b/devine/core/manifests/dash.py
index aac0e68..6a53bfd 100644
--- a/devine/core/manifests/dash.py
+++ b/devine/core/manifests/dash.py
@@ -207,7 +207,12 @@ class DASH:
                         language=track_lang,
                         is_original_lang=language and is_close_match(track_lang, [language]),
                         descriptor=Video.Descriptor.DASH,
-                        extra=(rep, adaptation_set),
+                        data={
+                            "dash": {
+                                "representation": rep,
+                                "adaptation_set": adaptation_set
+                            }
+                        },
                         **track_args
                     ))
 
diff --git a/devine/core/manifests/hls.py b/devine/core/manifests/hls.py
index fa89f32..08db12f 100644
--- a/devine/core/manifests/hls.py
+++ b/devine/core/manifests/hls.py
@@ -116,7 +116,11 @@ class HLS:
                 bitrate=playlist.stream_info.average_bandwidth or playlist.stream_info.bandwidth,
                 descriptor=Video.Descriptor.HLS,
                 drm=session_drm,
-                extra=playlist,
+                data={
+                    "hls": {
+                        "playlist": playlist
+                    }
+                },
                 # video track args
                 **(dict(
                     range_=Video.Range.DV if any(
@@ -166,7 +170,11 @@ class HLS:
                 is_original_lang=language and is_close_match(track_lang, [language]),
                 descriptor=Audio.Descriptor.HLS,
                 drm=session_drm if media.type == "AUDIO" else None,
-                extra=media,
+                data={
+                    "hls": {
+                        "media": media
+                    }
+                },
                 # audio track args
                 **(dict(
                     bitrate=0,  # TODO: M3U doesn't seem to state bitrate?
diff --git a/devine/core/tracks/track.py b/devine/core/tracks/track.py
index f15f7ef..39e3c27 100644
--- a/devine/core/tracks/track.py
+++ b/devine/core/tracks/track.py
@@ -35,7 +35,7 @@ class Track:
         name: Optional[str] = None,
         drm: Optional[Iterable[DRM_T]] = None,
         edition: Optional[str] = None,
-        extra: Optional[Any] = None,
+        data: Optional[dict] = None,
         id_: Optional[str] = None,
     ) -> None:
         if not isinstance(url, (str, list)):
@@ -54,6 +54,8 @@ class Track:
             raise TypeError(f"Expected id_ to be a {str}, not {type(id_)}")
         if not isinstance(edition, (str, type(None))):
             raise TypeError(f"Expected edition to be a {str}, not {type(edition)}")
+        if not isinstance(data, (dict, type(None))):
+            raise TypeError(f"Expected data to be a {dict}, not {type(data)}")
 
         invalid_urls = ", ".join(set(type(x) for x in url if not isinstance(x, str)))
         if invalid_urls:
@@ -74,7 +76,7 @@ class Track:
         self.name = name
         self.drm = drm
         self.edition: str = edition
-        self.extra: Any = extra or {}  # allow anything for extra, but default to a dict
+        self.data = data or {}
 
         if not id_:
             this = copy(self)