Time Values

Time values returned from an Aspen Server are specified in one of two forms: absolute time or intra day time.

Absolute Time

Absolute time is time measured as the number of minutes since 12:00 a.m., January 1, 1900, at the International Date Line. All absolute time values are stored in the ASPEN_TIME format and can be converted to and from ANSI standard time formats using the AspenTimeToANSITime() function and the ANSITimeToAspenTime() function.

Conversion from absolute time to a specific local time requires a time zone value. There is a time zone value associated with every Server, exchange, and financial instrument. This value may also be determined from the following figure:

Note there are two values for many time zones. The first indicates that standard time is used throughout the year. The second indicates that the daylight-saving or summer time rules should be used at the appropriate time of year. Thus, if time zone 31 is specified (Eastern Daylight Savings time (EDT)) the time conversion routines check to see if the daylight-saving time is in effect for the given date. If it is in effect, the time is corrected for daylight saving times, otherwise the standard (EST) time is returned.

The Aspen Server has the capability to add customized time zones for any locale. The API can use Customized time zones. See the Server documentation for detailed information on user-defined time zones.

Every piece of information stored in a Server's database is tagged with an absolute time. For example, every financial trade is tagged with the exact minute in which it occurred. Likewise, artificial constructs such as high-low-open-close bars (of any duration) are tagged and referenced by the absolute time at which their interval begins.

Intra Day Time

Intra day time indicates the number of minutes since 12:00 a.m. in a specific time zone on any day. For example, intra day time is used to define daily opening and closing times of an exchange's trading periods.

Why is Aspen time is different than ANSI time?

Aspen Time is different than ANSI time because ANSI Time orients itself to January 1, 1970. Many financial instruments, stocks and commodities, began trading prior to this date. Were Aspen Research Group, Ltd. to use ANSI time, Aspen products would be unable to provide historical data on any instrument prior to 1970. Hence, Aspen time orients itself to January 1, 1900.