It probably hasn't been documented yet.
Here is the S28 DSFL draft: https://www.youtube.com/watch?v=vkFNIbXa0k8
When you create a player, your Sxx number is your ISFL draft class, but everyone plays 1 year in the DSFL before being drafted in the ISFL. So the newest group, S29 players, have just gone through the S28 DSFL draft, and next offseason, will experience the S29 ISFL draft. Hope that helps!
Here is the S28 DSFL draft: https://www.youtube.com/watch?v=vkFNIbXa0k8
When you create a player, your Sxx number is your ISFL draft class, but everyone plays 1 year in the DSFL before being drafted in the ISFL. So the newest group, S29 players, have just gone through the S28 DSFL draft, and next offseason, will experience the S29 ISFL draft. Hope that helps!