World time is something I keep track of. It is mostly out of the need to, but something I do near flawlessly. And -4 GMT does exist. British Virgin Islands, Dominican Republic, and so on use it. When I think -4, I think warm weather and good vacation, not the foot of snow fallen in the past few days where I live. It is hard to do at times so I can see how people can get messed up. You must remember that even though you put a company name on it, humans still work it. We are all prone to errors and people always forget that. Humans are humans. There has never been and never will be a perfect one.