Last year, Apple updated its podcast spec for iOS 11. They added support for seasons, new episode types, and new ways to order and display episodes. Many Apple users got their first taste of these new features when iOS 11 went public in September 2017.

Apple’s changes made it possible for shows like Serial to have more control over how their stories are displayed, grouping episodes into seasons, and showing them in the proper narrative order.

Apple’s changes also formalized support for publisher-created conventions like trailers and bonus episodes:

Native season numbers, episode numbers, and trailers weren’t possible until iOS 11

On a technical level, Apple’s updated spec introduced four new tags:

<itunes:type> ( episodic or serial )

( or ) <itunes:season> for season numbers

for season numbers <itunes:episode> for episode numbers

for episode numbers <itunes:episodeType> ( full , trailer , or bonus )

Because I’m a podcast plumbing nerd, I decided to track the adoption of Apple’s new tags over time. I watched the Apple Podcasts US Top 200 very closely for one year, monitoring the shows listed there for the presence of these new tags.

Here’s what adoption looked like for the first year: