IntlDateFormatter manual doesn't include enough parameter explanation

From manual page: https://php.net/class.intldateformatter

There are not enough explanations of constructor parameters.

1. What are valid values for $locale? I happen to know that locale is not just en-US or fa-IR and it is like fa_IR@calendar=persian

2. What are valid values for $pattern? I can see y, m and d in combinations, but how do I specify time pattern in input? for example when on GMT it is still 9PM, it is already next day on GMT+8

3. And finally which TRADITIONAL calendars are supported?
   For example, in Saudi Arabia, Iran and a few other countries, TRADITIONAL calendar returns official calendar, but In USA, TRADITIONAL is the same as GREGORIAN. This means passing date through format, will change it to official calendar of country for first case but will not touch it for second case, which is desired effect in my case

   However for a Chinese speaking person in Malaysia TRADITIONAL Calendar is not official calendar which means in a global website simply passing every date through format will not return official date.
   To address this, I need to know which Traditional Calendars are supported and in my code change them accordingly

Start with the IntlDateFormatter manual page at https://php.net/class.intldateformatter and review the constructor-parameter documentation. Research valid locale forms, date and time pattern syntax, and supported TRADITIONAL calendars; the work is done when these questions are answered clearly with appropriate examples or references.