WTA Premier Tournaments.

[nuraman00]

I looked at wiki:

WTA Premier tournaments - Wikipedia, the free encyclopedia

And saw this:

Four "Premier Mandatory" events in Indian Wells, Key Biscayne, Madrid, and Beijing with prize money of $4.5 million.

Five "Premier 5" events in Doha, Rome, Cincinnati, Toronto/Montreal, and Wuhan with prize money of $2 million.

Are these mandatory? I noticed Serena rarely plays in Doha.

Wuhan is new this year, it will be in late September.

Tokyo and Dubai used to be Premier 5, but are reduced to lower categories this year (partially to make room for Wuhan). But even when they were Premier 5's, Serena rarely played in them.

I guess Premier Mandatory is "mandatory", but Premier 5 is not?