       adjusted = adjustment
     new Date(adjusted)
 
+  # The all purpose exported function.
   exports.tz = tz = (date, splat...) ->
+    # Assert that we've been given a date.
     throw new Error "invalid arguments" if not date?
+
+    # Create a default request.
     request = { zone: "UTC", adjustments: [] }
+
+    # Arguments with a `%` are date formats. Arguments that match a timezone are
+    # timezones, while arguments that look like locales are locales. If nothing
+    # matches, we assume that it is date math.
     for argument in splat
       argument = String(argument)
       if argument.indexOf("%") != -1

        throw new Error "unknown locale" if not request.locale
      else
        request.adjustments.push argument
    request.locale or= LOCALES.en_US
    if date.getTime
      date = date.getTime()
    else if typeof date is "string"
      date = parse date, request
    for adjustment in request.adjustments
      date = adjust adjustment, request
    if request.format
      toString date, request
    else

    { format, locale, zone } = request
    [ offset, output ] = [ new Date(date), [] ]
    tzdata = TIMEZONES.zones[zone]
    offset = wallclock(offset, tzdata) if zone isnt "UTC"
    while format.length
      match = /^(.*?)%([-0_^]?)([aAcdDeFHIjklMNpPsrRSTuwXUWVmhbByYcGgCx])(.*)$/.exec(format)
      if match
