In 2007, Daylight Savings Time was expanded to a wider range of dates in the US.  PHP scripts may display the wrong time if the new timezone descriptions have not been loaded on the IBM i.  This article explains how to find the IBM instructions to update IBM i for the current DST start and end dates.


IBM i, any currently supported version.


Please update your system with the new DST timezone descriptions.

You can also update your system immediately. On the above listed page, click the link labeled "Daylight Saving Time Manual Instructions".

On the page that comes up, find "Operating System Daylight Saving Time Manual Instructions" and expand the topic by clicking the blue arrow. Then, find your time zone on the list, and expand that topic. Follow the instructions for your time zone.

For newer versions of IBM i, you just need to make sure you have the correct value specified for the QTIMZON system value.  This table, from the article linked to above, tells the correct values.

Time zone descriptionNew 2007 rules QTIMZON valuePrior  QTIMZON value
Atlantic TimeQN0400AST2QN0400AST
Eastern TimeQN0500EST3QN0500EST
Central TimeQN0600CST2QN0600CST
Mountain TimeQN0700MST3QN0700MST
Pacific TimeQN0800PST2QN0800PST
Alaska TimeQN0900AST2QN0900AST
Hawaii-Aleutian TimeQN1000HAS2QN1000HAST