@LostInParadise No, I’m not confusing it. Every time zone in the world is plus or minus UTC Time.
Tokyo is currently +9, Tokyo is across the dateline from the US. US east coast is – 4 hours currently. UK is +1 hours right now for the summer. Time is always stated plus or minus UTC/GMT or pilots and military will often call it Zulu time. It’s easy to figure out the hours traveled by plane if you stay in one time, since you are crossing time zones. There are more reasons than that for pilots to use Zulu.
Here is a website for time. Pretty much any website will show time in regards to GMT, never the international date line. I looked up a couple cities same website. NY: https://www.timeanddate.com/time/zone/usa/new-york
London (which will go back to GMT when the time shifts again for daylight savings) https://www.timeanddate.com/time/zone/uk/london
Tokyo: https://www.timeanddate.com/time/zone/japan/tokyo
It says right on your link that UTC is used for time. The International Date Line (IDL) is located at about 180° east (or west). It is halfway around the world from the prime meridian (0° longitude), the reference point of time zones, which runs through Greenwich, UK.
But, maybe you mean something that I’m not understanding.