The specification https://yaml.org/spec/1.2/spec.html refers to some tags defined in http://yaml.org/type/

In 2.4. Tags there are links and examples for tags:
https://yaml.org/type/binary.html
https://yaml.org/type/omap.html
https://yaml.org/type/set.html

In 10.4
The tag repository is intentionally left out of the scope of this specification. This allows it to evolve to better support YAML applications.

In https://github.com/yaml/yaml/wiki/YAML-1.2-Changelog there is a link in section other:
TODO Include missing things from https://eemeli.org/yaml/#version-differences