If you were going through a custody case in Texas, you might be hearing the term Expanded Standard Possession Order or Standard Possession Order. An Expanded Standard Possession Order just affords the parent who is not the primary parent. So the parent who is exercising possession and access the ability to have the children overnight. So if you are ordered to have possession of the children on Thursdays and first, third and fifth weekends, then you will have the child starting on Thursday whenever they leave from school or at 06:00 P.m.
Whatever your order says and that you will have them overnight instead of just from six to 08:00 P.m. The same situation on the weekends if you have them each one third and fifth, then starting Friday when school ends all the way until Monday when the kids go back to school, you'll have the children rather than returning them to the other parent at six on Sunday on those first start and pick weekends.