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Time Zone Overview and Terminology

Dynamics AX 2009

One Microsoft Dynamics AX Application Object Server (AOS) installation can meet the business needs of a company that has operations across multiple time zones. All date/time values are stored in Coordinated Universal Time (UTC).

When a date/time value is retrieved and displayed on a form, the date/time is shown in the user's preferred time zone. If the date/time value is edited and stored again, the value is converted from local time to UTC for storage.

The following table defines terms that are used to discuss time zones.

Term

Definition

Application DateTime fields

DateTime fields in the database that are not automatically created by the AOS. Microsoft Dynamics AX ships with several application DateTime fields. Custom DateTime fields can also be added.

Examples could be ActivityStartDateTime or MeetingEndDateTime.

Date/time

A generic name for a single value that contains both date and time.

The types that hold date/time data are:

  • X++ – utcdatetime

  • Database table field – DateTime

DST

Daylight Savings Time. A rule that governs sudden jumps in the local time within any given time zone. The jumps are usually one hour. The jumps revert back, usually at the end of the winter season.

Governments set DST rules within a time zone. Changes to DST can shift the meaning of date/time values already stored.

Microsoft Dynamics AX provides a mechanism to adjust date/time values to correct for changes to DST rules.

GMT

Greenwich Mean Time. The local time at the longitudinal meridian that passes through Greenwich, England.

GMT is used as the common reference among all time zones.

Local time

Time for one particular time zone.

System DateTime fields

DateTime fields in the database that are automatically created, populated, and maintained by the AOS. The user cannot modify these fields.

Actual instances include CreatedDateTime and ModifiedDateTime.

Time zone

Any area of the Earth in which local time differs from its immediate neighbor. Consecutive time zones usually differ by one hour, or by DST rules.

Each time zone can have its own DST rules.

Update of time zone rules

Microsoft occasionally releases patches that update time zone rule data, after governments change the time zone rules. Updating the rules does not involve any upgrade of executable code.

Upgrade of Date and Time fields to DateTime

The upgrade from any product version prior to Microsoft Dynamics AX 2009 involves upgrading the product's executable code, database tables, and more. This is a one-time task.

This task replaces Date and Time field pairs with one DateTime field. It also updates time zone rule data.

UTC

Coordinated Universal Time. UTC is GMT that is updated with leap seconds (to account for the slowing of the earth's rotation).

UTC is intended as the replacement for the older concept of GMT.

The time zone features in Microsoft Dynamics AX can be categorized as shown in the following table.

Feature

Description

Time Zone Related Types

  • The utcdatetime intrinsic type in X++.

  • The DateTime field type on tables.

  • The date/time controls on forms and reports.

  • The Timezone enumeration.

Convert from Time Zone Before Persisting in X++

  • X++ programmer's obligation to convert local date/time values to UTC before storing them by calling insert_recordset.

  • The use of several DateTimeUtil methods in X++.

Time Zone and DateTime Display Controls

  • DateTimeEdit on Form.

  • DateTime on Report.

  • WebDateTime on Web Form.

  • DateTime on Web Report.

Time Zone and Updating the Hidden *TZId Field

  • How the system automatically coordinates a *TZId field for each DateTime field on a table.

  • How UTC values can become invalid when governments redefine time zones and DST rules.

  • The actions of updates that Microsoft can issue to adjust for time zone and DST redefinitions.

  • Details about time zone information hidden inside the utcdatetime intrinsic type.

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