> The functions defined in libxo are used to generate a choice of TEXT, XML, JSON, or HTML output. A common set of functions are used, with command line switches passed to the library to control the details of the output.

https://man.freebsd.org/cgi/man.cgi?query=libxo&sektion=3&ap....

See ps(8) for example use: https://man.freebsd.org/cgi/man.cgi?query=ps&apropos=0&sekti...