All service agreement lines that are attached to the service agreement are created with this date as their default start date. The start date can be changed.
Additionally, service orders cannot be automatically created for any period that is before this date.
Example
If a service agreement and lines have a start date of 01-01-2007 and you try to create service orders automatically from 01-12-2006 until 31-01-2007, service orders are only created for the period 01-01-2007 until 31-01-2007.