Talk:Partials/Updates/2017 January 25th/@comment-27302076-20170125110705/@comment-26912384-20170125121635

They stand for "New type exercise fleet 1st Group",  "New type exercise fleet 2nd Group", and "Everyone". Basically, you'll get different exercise opponents from different pools depending on which button you pushed, or which pool you chose. Apparently, the opponents from the new 1st Group will be tougher but there will also be greater rewards for winning.

Feel free to correct me though, I'm not 100% sure.