Extended Bopomofo. There is also a variant, called <a href="//commons.wikimedia.org/wiki/File:Extended_Bopomofo_MBE.svg" title="File:Extended Bopomofo MBE.svg">MBE</a>.
<a href="//commons.wikimedia.org/wiki/User:Fauzty" title="User:Fauzty">User:Fauzty</a>
CC BY-SA 3.0
<span class="int-own-work" lang="en">Own work</span>