[1] Post Type Discovery () <https://www.w3.org/TR/2016/WD-post-type-discovery-20160728/>
[2] Post Type Discovery () <https://www.w3.org/TR/2016/WD-post-type-discovery-20161028/>
[3] Post Type Discovery () <https://www.w3.org/TR/2017/WD-post-type-discovery-20170614/>
[4] Post Type Discovery () <https://www.w3.org/TR/2017/WD-post-type-discovery-20170801/>
[5] Post Type Discovery () <https://www.w3.org/TR/2018/NOTE-post-type-discovery-20180118/>
[6] Post Type Discovery () <http://ptd.spec.indieweb.org/>
[7] Post Type Discovery () <https://www.w3.org/TR/2018/NOTE-post-type-discovery-20180118/>