Use time fields to store:
•times you need to sort or search through
•times used in calculation formulas or summary fields
•The separators in time fields and the order in which the time parts appear depend on the system formats set for the file and the display format for the field. For information on changing the display format for a field (for example, 11:09 PM or 23:09), see Specifying formats for date, time, or timestamp fields.
•FileMaker Pro Advanced stores times as the number of seconds since midnight. Therefore you can calculate times before or after a given time by subtracting or adding a number of seconds. For example, in a calculation field whose result is a time, the following formula calculates the time one hour (60 seconds to a minute * 60 minutes to a hour = 3600 seconds) after the value in a time field named TimeStarted:
TimeStarted + 3600