The asciidoc(1) --backend option is also used to install and manage backend plugins.

• A backend plugin is used just like the built-in backends.
• Backend plugins take precedence over built-in backends with the same name.
• You can use the {asciidoc-confdir} intrinsic attribute to refer to the built-in backend configuration file location from backend plugin configuration files.
• You can use the {backend-confdir} intrinsic attribute to refer to the backend plugin configuration file location.
• By default backends plugins are installed in $HOME/.asciidoc/backends/<backend> where <backend> is the backend name.