As with most other computer system issues, Year 2000 issues can occur in any level of technology. You should be aware of and understand what levels of computer technology are used at your site and in your applications. This will help you identify exposure points to investigate for potential Year 2000 issues. It is important to ensure all technology levels of your systems are Year 2000 compliant.

1. Hardware

This includes the specific chip architecture (e.g., Intel Pentium, Sun SPARC, DEC Alpha, HP PA-RISC, etc.) and the machine's internal clock. The system date is provided at the hardware level by the internal clock. Many system clocks will return the value "1900" for Year 2000. These issues may be addressed by either firmware changes from the hardware vendor or by operating system patches. Check your hardware vendor's Web site and your operating system vendor's Web site for Year 2000 issues.

2. Operating Systems

The operating system, including the file system, stores and manipulates dates. The bulk of date processing and system date management occurs at this level of your system. Even many recent operating systems require upgrades to be fully Year 2000 compliant. Check your operating system vendor's Web site for Year 2000 issues.

3. Databases and Files

Databases include the set of files, DBMS databases, and spatial data used by your applications. Dates can be stored in any of your databases. Most of the time, you would use application-specific date types to store and manage date information (e.g., an attribute item of type DATE in your DBMS).

However, if you implemented custom date types in your data files as type text or numbers, you may have chosen to store only a two-digit value for the year (e.g., "95" instead of "1995"). You should check your databases and applications to ensure that their data management is Year 2000 compliant for date handling. You should also ensure that any custom date storage and handling you have implemented in your data schema is based on four-digit years or that you have implemented an unambiguous method for processing two-digit years stored in custom date fields.

4. Applications and Run-Time Libraries

Applications are software that run on your operating system and work with various databases. ArcInfo and ArcView GIS are examples of Esri applications. In addition to Esri software, you should ensure that other applications you use are Year 2000 compliant.

Applications also rely on run-time libraries and other embedded technology. Esri has ensured that embedded technology in its applications is Year 2000 compliant for the functions utilized by our applications. However, you should check for compliance of other applications and their run-time libraries for technologies you have added to Esri applications.

5. Custom Code

Custom applications are those built on top of Esri software or that utilize Esri software components such as applications built with MapObjects or ArcInfo ODE. It is definitely possible to build custom code that is not Year 2000 compliant even though the underlying applications are Year 2000 compliant. For example, any date handling in custom code may use only two-digit years instead of four-digit years, and dates could be reported by your custom code by appending the phrase "19" in front of a two-digit year.

Year 2000 issues are most likely to occur in custom code. You should establish guidelines for testing your custom code to ensure that they are Year 2000 compliant. Accept only Year 2000 certified applications from third party developers.

Summary

In order to gain a further understanding of the various technology layers at which Year 2000 issues may occur, you should check your operating system vendor's Year 2000 Web site. Microsoft has a particularly good Web site for understanding these technology layers. Visit the ArcUser Jump Station for a direct link to this portion of the Microsoft site.

Computer systems have five layers of technology. Year 2000 issues can occur at any level of technology. It is important that you take steps to ensure Year 2000 compliance at each level of your system.