KnowledgeBase 00061: Moving the Two Digit Year Number Range

Multivalue database products have always adopted a convention that a two digit year number represents a date in the range 1930 to 2029, a range that is roughly centred on the point at which the data model was created. We are rapidly approaching the upper limit of this range and the time has come to consider changing how two digit year numbers are interpretted.

The YEARBASE Configuration Parameter

In common with many other multivalue products, QM provides a way to move the 100 year range adopted for two digit year numbers. In QM, this is done by setting the YEARBASE configuration parameter to the start year of the range. This parameter defaults to 1930 for compatibility with other products.

YEARBASE is a private configuration parameter that takes its initial value from the QM configuration file but is maintained separately for each active QM session and can be modified with, for example,

   CONFIG YEARBASE 1970 

Application Issues

It is strongly recommended that any application that allows entry of dates with two digit year numbers should reflect these back onto the screen with all four digits so that the user can see any possible unwanted effects of applying the 100 year range.

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