diff --git a/yt_dlp/extractor/common.py b/yt_dlp/extractor/common.py
index b75e806233..01fecdf572 100644
--- a/yt_dlp/extractor/common.py
+++ b/yt_dlp/extractor/common.py
@@ -392,6 +392,8 @@ class InfoExtractor:
     chapters:       A list of dictionaries, with the following entries:
                         * "start_time" - The start time of the chapter in seconds
                         * "end_time" - The end time of the chapter in seconds
+                                       (optional: core code can determine this value from
+                                       the next chapter's start_time or the video's duration)
                         * "title" (optional, string)
     heatmap:        A list of dictionaries, with the following entries:
                         * "start_time" - The start time of the data point in seconds
@@ -406,7 +408,8 @@ class InfoExtractor:
                     'unlisted' or 'public'. Use 'InfoExtractor._availability'
                     to set it
     media_type:     The type of media as classified by the site, e.g. "episode", "clip", "trailer"
-    _old_archive_ids: A list of old archive ids needed for backward compatibility
+    _old_archive_ids: A list of old archive ids needed for backward
+                   compatibility. Use yt_dlp.utils.make_archive_id to generate ids
     _format_sort_fields: A list of fields to use for sorting formats
     __post_extractor: A function to be called just before the metadata is
                     written to either disk, logger or console. The function