pg_service file questions

Hi,

I was scanning through the postgresql documentations when i came across this webpage: PostgreSQL: Documentation: 15: 34.17. The Connection Service File<https://www.postgresql.org/docs/current/libpq-pgservice.html> . I am fairly new to database and i have a few questions regarding this:

1. Is pg_service.conf and .pg_service.conf (with a dot at the front) different files?
2. The documentation stated that the .pg_service.conf is named %APPDATA%\postgresql.pg_service.conf on windows which is a directory i can not find.
3. The documentation also stated that we can check for the sysconfigdir environment variable and point it to somewhere else, but when i checked for the sysconfigdir path, it is pointing to C:/PROGRA~1/POSTGR~1/15/etc which again, is a directory i can not find : to be specific, i can not find the etc file stated in the pathing.

So where should i put this pg_service file and does it link with the database itself?

Thank you
Best Regards
Jun