timezone thus: "3pm CET", "3pm Amsterdam" (major cities in a timezone are recognized)
result "... in ..." a different timezone , e.g. "3pm in London" (gives the answer "4pm BST" during summer
because it means "3pm UTC in London"); "3pm CET in London" to convert timezones
or enter a Unix timestamp (always UTC, never a timezone)
but can show the result locally: "1298865600 in New York"
slashes interpreted in European style d/m/y not US m/d/y
times before 1 January 1970 show up as negative unix times, but that's OK
it's very simple: mostly using the php date
and strtotime functions
a time calculator