Hello Daryl,
Our sample CCLXRULS(TIMECHNG) rule and OPS/REXX program CCLXSAMP(TIMECHNG) are samples you can modify to meet your needs.
You are correct in your assessment that the Global Variable GLOBAL0.TIMECHNG is not validated for duplicate entries.
Currently the sample code only validates that the Global Variable has been previously created and if today is a scheduled Daylight Savings day.
Would you be ok submitting this as an Idea instead Daryl?
Cesar